How Pagers Got Their Beep

The modern commercial paging service got its start with a family medical emergency in the early 1920s. Sherman Amsden couldn't reach his doctor who was out of the office and didn't have a secretary to answer the phone. Amsden decided the way to solve that problem was to have a central operator answer doctors' phones and take messages. The doctors could call in from wherever they happened to be and get their messages. He named his telephone answering company Telanserphone. The service was a commercial success, but doctors were still hard to get in touch with. That lead to the next advance, the radio pager.

Amsden teamed up with inventor Richard Florac to create with a two tube radio receiver in a plastic box that could be easily slipped into a coat pocket. Aircall was the first radio paging service, but it didn't get launched until 1950 and it didn't beep. Instead, subscribers would turn on the receiver from time to time and listen to a repeating series of numbers. If they heard their 3 digit code, they knew a message was waiting.

Another prolific inventor, Al Gross, also came up with a pocket pager in 1949, which was used by the Jewish Hospital in New York starting in 1950.

Basic "beepers" are not that far removed from that early technology. They still contain a radio receiver that operates in the VHF or UHF bands. They've shrunk to about half the size of Florac's ingenious receiver design. Solid state technology lets the pager take over the job of listening for the code numbers, now called capcodes, so you don't have to. The simplest pagers emit a beep when they hear their assigned code number. That's where they got the nickname "beepers." For silent operation, a motor with an off-center flywheel was added so that the entire pager would vibrate to indicate a message.

Motorola has been the big name in pagers ever since that term was first used to describe a Motorola system in the 1950s. The Motorola developed FLEX (FLEXible wide area synchronous protocol) signaling standard introduced in 1994 is the protocol of choice for one-way numeric and alphanumeric pagers. The complementary ReFLEX standard is used for two-way messaging. Both operate in the 900 MHz band on channels that are multiples of 25 KHz wide.

The traditional tone pager beeps or vibrates while the numeric pager also displays phone numbers and other numerical messages on a small liquid crystal display. The alphanumeric pager has an upgraded display that can show text messages. All of these are one-way pagers. They only have a radio receiver and decoder, so the paging service has no way of knowing if you actually received your message. They typically have better signal penetration into buildings than cell phones, but that doesn't mean they're sure to work down in the sub-basement. If you absolutely want to make sure you get your messages, you need a two-way pager.

The difference between one-way and two-way paging is the addition of a transmitter within the two-way pagers. This adds a couple of important new capabilities. First, you can send messages as well as receive them. Two-way pagers have little keyboards as well as multi-line displays. Second, a two-way pager can respond to the paging service to acknowledge receipt of a message. If you happen to be flying coast to coast when somebody sends you a text message or page, the system will keep trying to reach you until you have landed and are in range of a paging tower. The deluxe setup is a two-way pager with nationwide paging service.

More than 50 years after its introduction, radio paging has grown to millions of users all over the world. Pagers are a simpler and less expensive technology than cellular phones. You may prefer to get non-intrusive alerts and messages via pager rather than always engage in a voice conversation. The deaf and hard of hearing find two-way pagers to be an enabling technology.

Update: As of 2010, the functions of pagers have been largely replaced by cell phones and smart phones. Use the Cell Phone Plan Finder to check out the top phones and associated wireless service plans.

Turning Junk Frequencies Into Gold

We take the 2.4 GHz WiFi band for granted these days. Hotspots, wireless routers and access points are so prolific that it seems reasonable that this was all carefully planned and allocated. WiFi does have it's own special frequency allocations, right? Wrong!

WiFi Hotspots are actually using a chunk of radio spectrum that was originally carved out as a toxic dump for radiation that no one wanted in their backyard. It's called the ISM or Industrial, Scientific and Medical band. There are all sorts of ISM frequencies assigned by the FCC. They range from 6.78 MHz in the shortwave band through 245 GHz in the EHF or Extremely High Frequency range. The ones we're mostly interested in today are the 900 MHz band from 902-928 MHz, the 2.4 GHz band from 2.4 to 2.5 GHz, and the 5.8 GHz band from 5.725 to 5.875 GHz. Does that middle one sound familiar? It's the frequencies used by 802.11b & 802.11g WiFi.

The ISM bands were originally carved out to allow unintentional radiators some place to radiate. Unintentional means that no one is trying to communicate. It's radiated energy that is a byproduct of some industrial, scientific or medical process. What sort of equipment? Turn your microwave oven around and look at the information on the back. Or if it weighs too much, look at the specifications in the manual that came with it. What frequency does it operate on? My late model Sharp Carousel Microwave says 2450 MHz which is also 2.45 GHz. Good grief. That's right in there with channels 8 and 9 of the IEEE 802.11b WiFi specification.

Yes, the ISM bands really were meant for things like commercial and home microwave ovens, industrial microwave heating like curing glued wooden parts, medical diathermy which is therapeutic heating of body tissues, and scientific instruments. For these applications to work they need to use radio frequencies and can't help but radiate some energy even when they are well shielded. These ISM assignments weren't set up as licensed bands because the emissions were a byproduct of other processes.

That changed in 1985 when the FCC opened up these bands for intentional radiators to give new technologies a place to go in the crowded radio spectrum. The requirements to put ISM frequencies to work include a fairly low radiated power of 4 watts or less and a no complaints policy. If your radio system suffers interference from a microwave oven or other equipment, too bad. You didn't buy a license to have exclusive use the channels so nobody is coming to your rescue.

At first blush, who would want these unprotected frequencies? Isn't operating on them just begging for trouble? Turns out that the interference situation isn't all that dire. ISM's attraction is license free operation with enough power for wireless phones, wireless networking and even video transmission. Cordless phones operate successfully on the 900 MHz, 2.4 GHz and 5.8 GHz bands. WiFi and Bluetooth have claimed 2.4 GHz. The 5.8 GHz band is being put to good use for such things as transmitting security camera video and is earmarked for WiMAX operation.

So why isn't the interference problem a show stopper? Partly because the range of both the intentional and unintentional signals is very limited. It's not like AM or Short Wave Radio where stations interfere with each other over hundreds and thousands of miles. The other big factor is the use of modulation techniques that are tolerant of interference. The two main forms of spread spectrum modulation, Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS) are used by telephones, 802.11b WiFi and Bluetooth. Another resilient modulation technique, OFDM or Orthogonal Frequency Division Multiplexing is used for 802.11a, 802.11g, WiMAX and Broadband over Power Line, to name a few.

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Cheap Business Continuity Insurance

What happens to your business when you can't do business? Disaster, right? You've built a business with personal investment, sweat equity, investor capital and lots of calendar time. Anytime that business is closed when it should be open, you lose sales and you may be losing something even more valuable; customers. Customers that normally come to you and now go elsewhere may never be back. If too many fail to return, YOU may not be able to come back.

There are a lot of risks out there that can put you temporarily or permanently out of business. One that you do have control of is your connectivity. Think about it. Just how are you doing business these days? Most companies, even primarily bricks and mortar operations, now have critical electronic umbilical cords for life support. You almost can't do business anymore without telephones and Internet service. Some companies also have private line services to tie their facilities together.

What happens when you lose your electronic lifelines? If you're selling hotdogs from a push cart, maybe this isn't a valid question. If you're a stockbroker, you're gone. If you sell online using your own servers in the next room, you're gone. If your point of sale terminals don't work, you might as well turn off the lights and go home.

Now, consider the economics of using an "expensive" T1 line versus a "cheap" DSL or Cable Modem line for your Internet connectivity. Many times you can get the same advertised bandwidth, 1.5 Mbps, with any of these services. DSL might be a minor expense of $50 to $150 a month. T1 can run as much as 10 times that amount, or even more. So why would a cost conscious business person pay a premium price for bits on a wire?

When everything is working perfectly, you might not be able to tell the difference. T1 dedicated Internet does have the same high speed for both upload and download and its bandwidth isn't shared with anyone else. So T1 does generally perform better than business DSL or any of the consumer grade Internet services. But that's not its most valuable property. It's the service guarantee that's key.

T1 lines come with something called an SLA or Service Level Agreement. This is part of the contract between you and the carrier that spells out how fast they'll respond to an outage in your service and how much they'll reimburse you when it fails. You typically get a credit on your bill depending on the duration of the outage, be it minutes or hours. Yes, you pay more to have this "insurance" policy, but it gives your provider a huge incentive to jump immediately on any problem you report and get it resolved quickly.

Contrast that with DSL or Cable modem Internet which are "best effort" services. With these services, the provider isn't tied to any guaranteed level of service. When the line goes out, they'll do what they can with the personnel available and eventually you'll get your service again. It might take hours, it might take days. When T1 goes down, it will typically get attention within 30 minutes, likely 4 hours at the most, even overnight.

So, what are the true costs versus the advertised prices of T1 service versus DSL? You can answer that yourself. What is a lost hour or lost day or two of Internet access worth? Will you fail to book $1,000 worth of business? $5,000? $10,000? If so, that DSL line that feeds your desktop computers and web server could wind up being MORE expensive after the first outage.

Your telephone service was never related to any of this until the advent of VoIP. Now if you lose the DSL service that carries your phones, computers and web server, you really are down for the count.

Only you can quantify the risk to your particular business of not going with professional grade connectivity, but there are some other options you should also consider. Integrated T1 service splits the T1 line between conventional phone lines and Internet access. You use this with a PBX system in place of individual phone lines. You might even save money by ditching the DSL and a dozen conventional phone lines, and replacing them with an Integrated T1 line that has 12 telephone channels and 768Kbps of Internet access. With that you get an SLA. Another option is to replace consumer type ADSL or business SDSL service with a fractional T1 line. You get a fraction of the bandwidth for a lower price, but it's got that important service level agreement.

T1 Rex has a dozen top tier competitive service providers with prices lower than you might expect for T1 dedicated Internet access, T1 Integrated voice and data service, fractional T1 lines, and T1 local and/or long distance telephone lines. We also have a team of experts that can help you choose the most cost effective service for your particular business situation. Get a competitive T1 price quote now.

Can Gigabit Hotspots Be Far Off?

Even while attention is being focused on WiMAX as the next big breakthrough in wireless networking, the capabilities of 802.11 WiFi have been quietly creeping up and up. Speeds have already increased one order of magnitude to over 100 Mbps in commonly available equipment. Combinations of new technology are now pushing that second order of magnitude toward the 1 Gbps level. Let's review how far we've come and why Gigabit WiFi hotspots may not be out of the question.

Our benchmark is 802.11b, the now ubiquitous standard that offers 11 channels in the 2.4 GHz band with 11 Mbps of bandwidth. Then came 802.11a which boosted that to 54 Mbps on the 5 GHz band. The 2.4 GHz band technology was then boosted by 802.11g to the same 54 Mbps bandwidth as "a." The "a", "b" and "g" technologies are the standards currently available. But why stop there?

No sooner was the 802.11g standard introduced, when a non-standardized "Super G" by Atheros Communications doubled the speed again to 108 Mbps. Super G has a number of enhancements that include sending data in bursts, bundling data frames together, and compressing data for transmission. It also uses a controversial technique called "dynamic turbo" that bonds 2 of the 11 available WiFi channels to create a double channel with twice the capacity. It's controversial because doubling up reduces the number of networks that can be operating in a given area. In practice, the limited range of WiFi is often confined to a single office, restaurant or dwelling with a few users, so it may make no difference at all.

Another technique that improves on the original wireless network performance is MIMO, the smart antenna technology called Multiple-Input Multiple-Output. MIMO sticks with one channel, but sends out at least 2 independent datastreams from two different antennas on that channel. That also doubles the bandwidth from 54 to 108 Mbps. The "pre-n" hardware you can buy now runs at that speed. However, MIMO isn't limited to only two datastreams. With sufficient processing power to sort out the jumble of signals arriving at the receive antennas, a 4X4 MIMO structure consisting of 4 transmitters and 4 receivers can boost throughput 4 times to 216 Mbps.

Now, combine MIMO with channel bonding and you are getting close to half a gigabit per second. Include the other enhancements of Super G and you are probably past that mark.

So, what's next? Larger MIMO structures? Bonding in more channels? Moving back to the 5 GHz band and spreading out to 100 MHz with Orthogonal Frequency Division Multiplexing (OFDM)? Actually, that might be it. Siemens demonstrated an experimental gigabit per second wireless system at the end of 2004 using these techniques. It was a lab demonstration, but now that we know it works...

Well, you know how fast technology can get to market once we know it can be done.

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MIMO Makes Radio Interference Your Friend

Radio interference is a bad thing, right? It's bad enough when someone else's transmission interferes with yours. But when your own signal interferes with itself, isn't that the worst? Well, it used to be. Now it can actually work in your favor.

The type of interference in question here is called multipath. It's pretty much what the name says. A radio signal from a transmitting antenna takes multiple paths to the receiving antenna. The signal we normally want is the one that flies like the proverbial crow in a straight line from transmitter to receiver. Those other paths come from the same transmitted signal bouncing off hills and buildings outdoors and walls and objects indoors.

You know that anytime waves of any type meet, they interfere creating hotspots and dead spots. A common experience of this is when you pull up to a stop sign and the FM station on your car radio gets distorted or cuts out. If you can creep a foot or so forward, it comes back in. That's multipath in action. Since the wavelength of an FM radio station is only about 3 feet long, moving a foot makes a big difference between the multipath signals adding and subtracting.

Wireless networks are built on radio transmitters and receivers. The same multipath effects occur at 2.4 GHz as they do at 100 MHz. The only thing different is that the wavelength of a 2.4 GHz signal is about 5 inches instead of 3 feet. Indoors there are lots of things for such a high frequency signal to bounce off. It's likely that your wireless router and notebook computer are bathed in a sea of multipath signals of varying strengths.

A classic way to reduce multipath problems is called spatial diversity reception. Two receiving antennas are used, separated by inches or feet. The receiver compares the signal strengths coming from each antenna and picks the one with the strongest signal. That helps, but you can still have strong and weak spots in any area. What if you could take advantage of that to get more bandwidth?

It sounds a bit counterintuitive to expect that interference can help increase bandwidth instead of reduce it. But that's what "smart antennas" using a technique called MIMO or Multiple-Input Multiple-Output do. The boost comes from transmitting two different streams of data on the same channel using two transmitting antennas. The resulting cacophony is sorted out by two receiving antennas and some clever processing algorithms. For instance, if a WiFi access point normally has a bandwidth of 54 Mbps, it could have as much as 108 Mbps for two independent streams of data.

What we normally get when there are two stations on the same channel is a jumbled mess of both signals or the stronger of the two overpowering the weaker one. But when you factor in the multipath cancellations that you can't avoid anyway, the two receiving antennas will not pick up both datastreams equally on both antennas. One will be stronger at the first antenna. The other will be stronger at the second.

The overall technique is referred to a spatial multiplexing rather than simple spatial diversity reception. The multiplexing refers to the inverse multiplexing that comes from combining two datastreams into one larger one to effectively increase bandwidth.

Does it work? You bet it does. It works so well that the IEEE is likely to include MIMO when it approves 802.11n, a WiFi standards upgrade that increases wireless data rates to 100 Mbps and beyond. As usual, manufacturers are getting out ahead of the standard and releasing pre-802.11n hardware. First was Belkin Pre-N Wireless Networking. Other companies have also released "pre-n" equipment with the benefit of an immediate speed and coverage improvement, backwards compatibility with existing "b" and "g" WiFi, and at least a hope that only minor upgrades will be needed when the official standard is released in a year or two.

Slicing and Dicing Digital Carriers

Digital carriers, such as T1 & T3 copper lines and OC3 through OC48 fiber optic lines, are something like roads. Smaller country roads merge into superhighways with enormous traffic capacity and then dissolve into multiple smaller roads again. When this is done with electrical and optical signals it goes by names like multiplexing, demultiplexing and inverse multiplexing.

The first telephones were not multiplexed. It was one conversation on one pair of wires. If you've seen those old time pictures of New York City crammed with telephone poles and a virtual net of phone wires overhead, you can see how this method gets out of hand quickly. The first improvement was to multiplex many telephone calls onto one set of wires. Multiplexing simply means merging a bunch of low capacity circuits into one big one. They did this using carrier signals at widely separated frequencies to create channels for the individual phone calls. It works similar to analog cable TV where the stations come to your set on one wire but are kept separate because each station is on its own channel. This is called frequency division multiplexing.

We think of frequency division multiplexing (FDM) as old hat, but its modern equivalent is wavelength division multiplexing (WDM) used in fiber optic carriers. Each wavelength, called a color or lambda, is also a separate frequency that is digitally modulated by the information it carries. All the colors travel on the same fiber strand without interfering with each other, just like all the TV channels travel on the same cable.

A purely digital form of multiplexing is TDM or time division multiplexing. Groups of bits are loaded onto a wire one after the other. The first 8 data bits may be channel 1, the next 8 can be channel 2, and so on. A T1 line builds 24 of these channels of 8 bits each. It then adds a framing bit at the beginning of this 192 bit stream so it can keep track of where the channels are. A multiplexer takes individual phone calls or modem channels and assigns them to particular channels. At the other end, a demultiplexer takes the bitstream apart and recreates the original 24 channels. Equipment that does this for telephone calls is known as a channel bank.

Now consider a bigger wireline such as a T3, or an optical carrier like an OC3. Instead of multiplexing individual small channels, these lines multiplex entire T1 or larger lines. An OC3 can multiplex 84 T1 lines or 3 T3 lines. Since all these lines are based on TDM, the multiplexing and demultiplexing is fairly straightforward. It's all based on channels having their fixed place in the bitstream.

Like a superhighway, a high speed digital carrier has interchanges known as add/drop multiplexers. These are the on and off ramps. The DS3 service for your building may well be "dropped off" from an OC3 fiber optic line using an optical add/drop multiplexer. Unlike the terminal multiplexers and demultiplexers at each end of the cable, the idea of an add/drop multiplexer is only to access certain channels while letting the others pass through unaffected. For wavelength division multiplexing, a newer device called a ROADM or Reconfigurable Optical Add Drop Multiplexer, can be remotely controlled to insert and drop particular wavelengths at a particular node in the network.

So what is inverse multiplexing? That's when you carry large amounts of traffic using lots of small carriers. A common example is bonding 2 or more T1 lines to make a larger capacity carrier. Bonding up to 6 T1 lines to get as much as 9 Mbps bandwidth from 1.5 Mbps individual T1 lines is often less expensive than buying one 45 Mbps T3 line that may be far more capacity than you really need.

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Wi-Fi Is Being Groomed As A Serious Carrier

Wi-Fi or Wireless Fidelity was invented as a way to build or extend a Local Area Network without being tethered by all those wires. It's basically Ethernet with the Ether put back in. I'm not sure if even the inventors realized what a buying frenzy for WiFi capability would result from getting rid of those wires. People who wouldn't go near a roll of Cat5 cable snatched up wireless routers and adaptor cards to network their homes and small businesses. Now you can almost get access points free after rebate at computer and office supply stores.

WiFi has gone from an accessory to a basic connectivity technology and has even become the Internet Service Provider of choice for some. You can hardly walk into a restaurant anymore without seeing a "Free WiFi Hotspot" sticker on the front door. WiFi at the present is doing exactly what the technology was designed to do. That is, transmit broadband network packets reliably throughout a room sized area. It's because WiFi has become SO prolific that it is now being asked to step into a greater role, that of telecommunications carrier.

It seems that everybody suddenly wants to be in the carrier business. The wireline telephone companies had 100 years to get it right. The cellular companies have been perfecting their act for about 30 and they're only now on the verge of offering high speed data everywhere they offer basic voice calls. The heat is on to make WiFi a third contender with WiMAX the distant up and comer.

So what new role is WiFi being asked to assume? It's the whole idea of voice, video and data convergence that is sometimes called the triple-play. If your network can deliver quality voice, video and data, then you can play in the same carrier game as the big telecom companies. Honestly, though, the real push is voice in the form of VoWi-fi or Voice over WiFi that hopes to compete with cellular for telephone service. VoWi-fi is VoIP gone wireless. There are even cell phone designs coming out that will work in a WiFi hotspot and then seamlessly switch to a cellular signal when you move out of WiFi range.

The only problem with this rosy scenario is that WiFi was never designed with differentiated levels of service in mind. Packets are packets are packets to the venerable 802.11 standard. But not for long. The IEEE will likely standardize a new set of Quality of Service extensions called 802.11e in the near future. In the meantime, the Wi-Fi Alliance, the industry certification group, has implemented its own pre-e extensions called WMM or Wi-Fi Multimedia.

The basic idea with both standards, WMM being a subset of the expected 802.11e, is that packets should get different priorities on the network depending on what they are carrying. Both voice and video are real-time data streams that turn ugly when pieces get dropped or delayed. Computer data exchanges such as email and web surfing are much less sensitive. Background activities like data backups to a central storage site are not fussy at all.

The way that QoS is implemented for WiFi is to tinker with the basic operation of collision prevention system. You can't have every device on the network talking at the same time or their packets will collide and nothing will get through. So they have to take turns. Each station listens for a quiet period and then waits a random time before trying to transmit. If it hears another station transmit, it stays silent and waits for the next opening. That's essentially how the classic Ethernet works on a wired network that uses hubs instead of switches.

Right now all WiFi devices have an equal chance at the radio channel. With QoS classes, voice and video devices get to wait a shorter time before transmitting their packets. They get to jump out sooner when the channel is clear and thus make the lower priority data-only devices wait longer. In effect, voice and video get a bigger percentage of the network time so that they have a better chance of staying intact when there isn't enough bandwidth for everybody to run at maximum speed.

With WMM and 802.11e, WiFi networks will be poised to handle VoIP and video phones, perhaps even before QoS is completely implemented on the wired corporate networks.

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When The Speed of Light Is Too Slow

If there is anything fast, it's light. Nothing is faster if you believe Einstein. The speed of light is so fast compared with everything else we experience that we tend to think of it as instantaneous. But it's not. There is even a small but imperceptible delay between the time you flick the light switch to ON and the time you see a room full of light.

Imperceptible is the key. Newton's laws of motion work just fine at the speeds that everyday things move. Us, cars, jet aircraft, even speeding bullets are too slow for the speed of light to have any effect. But communications is not in the material realm. We engage light to transmit information through fiber optic cables. Light's cousin, radio waves, are in the same electromagnetic family and subject to the same speed limitations. Believe it or not, that Einstein speed limit can cause us real grief.

Let's say you are in New York and want to talk to someone in Tokyo. Your voice will travel 6,760 miles. The speed of light is about 186,000 miles per second. That's 186 miles per millisecond. The fastest any signal could get between New York and Tokyo is about 36 milliseconds. Most of the way, the phone call will be carried by laser light in fiber optic cable. Light travels much slower in glass than it does in a vacuum or air. It's about 65% as fast or 120,900 miles per second. So the delay between when you speak and the person at the other end hears you is at least 56 milliseconds.

That 56 milliseconds of transport delay is called latency. In a real phone call the latency would be 1.5 to 3 times as long because the fiber optic cable isn't stretched between the two cities. It follows a longer path around the country and under the ocean. There are also electronic regenerators along the way that add their own latencies. That 56 milliseconds may well be least 84 to 168 milliseconds. To call half way around the world, about 12,500 miles, the delay just due to the speed of light would be 67 milliseconds, with a likely total latency of 101 to 202 milliseconds. At 250 milliseconds, the delay starts to become annoying.

Where does 250 milliseconds make a difference? Say you want to play a real time action game hosted on a server on the other site of the Earth. The round trip from mouse movement or keyboard entry to screen update is twice that or 500 milliseconds which is also half a second. Can you notice a half second lag?

Here's another example. Say you want to host a concert with musicians located in various countries around the world. You connect the various studios through digital fiber optic cables and combine all the vocals and instruments on your mixing board. A singer half way around the world will hear the mixed audio in their headphones a quarter of a second later than you do and you'll receive their voice a quarter of a second after they start singing. Does a half second make a difference in this case? You bet it will. No two performers will hear the same mix. Everybody will be slightly off in their timing.

Well at least you can make a phone call, right? Sure, as long as you avoid sending it through a satellite in geosynchronous orbit. Those birds are out there 22,300 miles away. The path is almost totally a vacuum, so the radio waves will travel or propagate at 186,000 miles per second. The satellite will hear you 120 milliseconds after you start speaking and will take another 120 milliseconds to send it to the party you called. That's 240 milliseconds best case. If every data packet was acknowledged before it was accepted, the delay would double to 480 milliseconds at a bare minimum. For voice, it's probably better just to shoot those packets up there and hope they come back intact. Even so, other latencies due to landline transport and routers that add perhaps 10 milliseconds each will push the total delay to the point where you have to treat satellite VoIP calls like walkie-talkies rather than full duplex telephones. Ping times, a measure of the round trip latency, have been reported over a second and about 850 milliseconds on average for two way satellites in geosynchronous orbit.

Want to call someone on Mars? It's a mere 35 million miles away so plan on your call taking 3 minutes to get there and 3 minutes to come back. Forget music on hold, you'll need background music while waiting for responses. The moon is a lot closer. When we establish a base there, you can call your friends 239,000 miles away. They'll hear you in about a second and a quarter. It's a mere two and half seconds round trip at the speed of light.

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WiMAX Moves Out

WiMAX, the 800 lb Wireless Gorilla, is starting to make its move. But isn't official WiMAX certification supposed to be in July? Yes, but who can wait that long?

Apparently, the answer is "no one." Pre-WiMAX technology is breaking out of the labs and moving into position world wide. No less a corporate giant than AT&T has announced it will start testing WiMAX in Middletown, N.J. in May. These test will focus on providing service up to 6 Mbps per user to a range of 2 to 6 miles for business customers. Both line of sight and non-line of sight transmissions will be tested. Success will make WiMAX a strong competitor to DSL, cable Internet, wireless, and even T1 dedicated data lines.

Meanwhile Tokyo is launching an ambitious city-wide WiMAX Metropolitan Area Network. Trials will start in the next few months and service will begin in December. This implementation will use AS.MAX base stations from Airspan Networks that are capable of bandwidth up to 50 Mbps.

Ireland is also a player. Irish Broadband expects to launch the start of a nationwide WiMAX network this year. No doubt, there will more announcements as WiMAX begins its move to blanket the globe.

WiMAX, Worldwide Interoperability for Microwave Access, is the big brother to WiFi wireless broadband. It has the ability to provide service up to a maximum of about 30 miles. Data rates within a few miles of the access point can soar to 70 Mbps. In about a year, WiMAX capability is expected to be built into notebook computers the way WiFi capability is included now. WiMAX is being billed as a MAN or Metropolitan Area Network while WiFi is targeted more as a LAN or Local Area Network.

All of the initial WiMAX tests and deployments are based on the 802.16-2004 standard that was ratified by the IEEE in June of last year. The pre-WiMAX equipment is expected to get its "WiMAX Forum Certified" stickers later in the year. Vendors have planned ahead for upgrade to the 802.16e extension for mobile operation when that is ready.

The importance of the WiMAX Forum Certification is proof that any manufacturer's equipment can operate with any other's that gets the certification. Manufacturers including Alvarion, Airspan Networks and Redline Communications are already running their own interoperability tests to avoid any unpleasant last minute surprises. This is especially important considering the amount of equipment that may already be in the field by the time the designs are blessed as officially WiMAX.

WiMAX has been standardized for both the licensed and unlicensed bands in the spectrum between 2 and 11 GHz and 10 to 66 GHz. To get things rolling, the WiMAX Forum is certifying equipment for the 3.5 GHz international band and the 5.8 GHz license free band.

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Gigabit Ethernet Leaves The Office

Corporate data networks have been steadily moving up the speed range from Ethernet to Fast Ethernet (FastE) to Gigabit Ethernet (GigE) and starting to implement 10 Gigabit Ethernet (10 GigE). Meanwhile, the lines that leave the campus are often much lower speed wide area networks. Something seems a bit out of balance with this model. Here's why it's like that and why it is likely that the corporate LAN is going to be stretched across town and across the country.

Before the big change waves of business practice re-engineering and supply chain integration, companies tended to be rather individual, isolated entities. The company network stayed within the walls of the company. Connections to the outside world tended to be T1 or PRI lines for the PBX phone system and X.25, frame relay, or T1 data lines between company locations. You called customers and suppliers on the phone. Paperwork was faxed back and forth or sent by overnight mail. Now it's just as likely that you, your customers and your suppliers all access the same database. The need for Internet access on every desk drove up the network bandwidth. Moving to voice and video over IP has multiplied the need again.

Today it's quite possible for company networks with the data capacity of fire hoses to be interconnected by external lines with the capacity of garden hoses. In some cases, it's still soda straws. That only works if most of your traffic stays in the building with just a trickle going outside. Otherwise there is this giant pressure on each end of the congested line. Data transfers slow to an annoying crawl. VoIP based phone calls break up and are dropped. Overnight data backups to an offsite storage facility can take so long that they can't be completed before the morning shift begins.

The obvious quick fix is simply to order bigger versions of the same pipes you have now. T1 lines can be bonded 2, 3, 4, 5, even 6 times. Then it makes more sense to switch to a T3 line. Multiple T3 lines can be replaced with an OC3 fiber optic carrier. OC3 becomes OC12, OC12 gets upgraded to OC48. Because the T-Carrier and Optical Carrier standards are all based on the same telco standards, they work well together. Because of their telephone network origins, they also have high reliability built-in.

Another way to go is directly to Ethernet. With the lines mentioned, your network traffic is converted from packet based IP to TDM (time division multiplexing) synchronous transmission and back again. With native Ethernet protocol, it stays as IP all the way. In many cases the protocol conversions may be transparent enough that it doesn't matter how the data is getting from place to place as long as it moving at the right speed. Native Ethernet vs Ethernet over SONET (Synchronous Optical NETwork) may be a wash.

On the other hand, where Ethernet transport service is available it has the advantages of simple interfacing and being easy to understand and manage. Metro Ethernet, offering high speed service within a city, is often available as standard Ethernet (10 Mbps), Fast Ethernet (100 Mbps), Gigabit Ethernet (1 Gbps) and sometimes 10 Gigabit Ethernet (10 Gbps). Redundant connections can offer the fault protection you get with SONET rings. You may also be able to lease dark fiber and light it with your own Ethernet termination equipment.

Managed Ethernet services have some other interesting options. One is ability to select intermediate bandwidths, such as 50 Mbps, 300 Mbps and 500 Mbps as well as the standard Ethernet speeds. This way you gain the cost advantage of buying only as much bandwidth as you need instead of only the order of magnitude standard increments. Ethernet connectivity is also available as both Ethernet Line which is a point to point service between two locations, and Ethernet LAN which interconnects multiple locations just like they were on a true local area network.

To find the best prices on Ethernet or SONET high speed data connectivity, let our GigaPackets service assist you. Our team can find multiple options from a dozen or more top tier vendors and help you select the most appropriate for your needs.

Upgrade Your Business Image

How are you perceived as a business professional? Working for a large corporation, much of your image as seen by customers is packaged by the company. But as a small business owner, independent sales agent, or professional consultant, your fate is pretty much in your own hands. Speaking of hands, what is that in your hand? Is it your business card?

Let's see what sort of impression this card gives. The card stock and typesetting give a polished look with your name, title, address and... Oh, oh. What sort of an email address is clientstalker666@junk4mail.com? That sort of thing is fine if you're a student or hobbyist. No way for a pro to look. What you want is something like yourname@yourcompany.com

First, a professional email address gives the impression that you are seriously in business and not just playing around. Second, it's a lot easier to remember than anything full of letters and numbers, and much easier to associate you with the business. If you want to be taken seriously, forget publishing those free email addresses including the one from your Internet service provider. At the very least, get a domain name service that offers email forwarding. Then you can keep your personal email address and publish only your business email. No one needs to be the wiser that your business mail is being forwarded to your personal email.

Fortunately, getting a professional email address is not expensive. For less than $10 a year, you can get a .com, .net or .org domain name with email forwarding from Domains With Us. Ideally, the domain name you choose is the same as the name of your company or something closely related. With that same $10 a year registration you also get domain name forwarding for your web site.

You do have a web site, right? It's a good idea to have one even if your business is strictly offline. At the simplest level, it can serve as a brochure for your business with contact information and a description of what products or services you offer. With more effort, it can be an online sales machine where customers can place their own orders when you're unavailable.

Once again, I'd suggest avoiding the free web sites, with a couple of exceptions. The first is any agent site provided by a company that you represent. These are professionally designed and coded with your agent ID. The URL is usually something ugly such as http://thecompanyyourepresent/?AgentID=yourpersonalcode

This is where URL forwarding is valuable. The same domain name you bought for your email forwarding can be forwarded to your website. Now you publish your domain name as http://yourcompany.com instead of that long ugly thing. Like the email, no one needs to be the wiser about where they are being sent when they enter that URL into their web browser or find it through a search engine.

The other exception to the free web site is the blog. Google lets you establish a blog at no charge with their Blogger service. The beauty of using a blog as your business web site it that the web design and tools come built-in. All you need to do is add content. Every time you have something to offer or comments about your industry you add a post to your blog. If you've been putting off getting a web site because design and maintenance is too time consuming, and paying someone to do it is too expensive, then you'll find getting started with a blog to be fast and easy. By the way, Telexplainer is a blog using the free Blogger service.

Now how about your phone number? A toll free business number gives a top-notch look at very little cost. People are also more likely to make the call to a toll free number because they don't have to pay. Fortunately, you don't have to pay much either. Toll Free numbers are available from Kall8 for a couple of bucks a month plus the cost of the calls. For more on how these can help you, read "Boosting Business With Toll Free Numbers."

Softphones Turn Computers Into VoIP Telephones

Telephones are for voice and computers are for data, right? Well, that's the way it used to be. That was back when telephones had their own network, the Public Switched Telephone Network (PSTN). Computers had their own network, the Internet. Then along came cellular phones that download email and web pages, and VoIP phones that let you talk over the Internet. Now you can mix and match almost to your heart's content.

Softphones are blurring the line between telephone and computer even further. A softphone is a telephone in software. It pops up on your computer screen and you make phone calls with it. You can even make phone calls while you are surfing the web or sending email with your computer.

That suggests some interesting possibilities. Download a softphone into your notebook computer and you have VoIP to go. You can take your regular VoIP phone service with you on business trips and vacations. All you need is a hotel, coffee shop or airport lounge that offers broadband access. There are no telephone roaming charges like you have with cellular because one access point is as good as another on the Internet. If you have an unlimited calling plan, there are no additional telephone charges no matter where you are. It even works overseas where you can get broadband access.

Say you are an independent sales agent. Set yourself down in a cafe that offers free WiFi, order up a cappuccino, and you can talk to your customers, look up information and even enter orders at your corner table. Or, drop by to see clients with your entire office tucked under your arm.

So how DO you turn a computer into a telephone? The softphone client is a program like a browser or email program. Part of it establishes a link to your Internet connection to transmit and receive VoIP formatted voice packets. Another part uses the sound card within your computer to convert from microphone audio to digital words, and to speaker audio from incoming digital words. This is called analog to digital (A/D) and digital to analog (D/A) conversion. Some computers have a separate digital signal processor (DSP) chip to do this. Many use an Audio Codec (Coder/Decoder) chip and signal processing software that runs on the computer's microprocessor.

Other parts of the softphone client handle signaling with your VoIP provider and create a graphical user interface on your screen that looks and operates much like any other phone. You get the usual controls, such as a keypad, dial and hang up buttons, microphone and speaker volume controls, special buttons for mute, call transfer and conference, phone book access and a call display. The display shows such things as your call status, dialed number, caller ID info and a call timer.

You can use the speaker and microphone that are built into your computer to make calls, but that's a lot like using a speakerphone and you might have echo problems. Softphones work a lot better when you use a headset with a separate microphone and earpiece. Just plug the connectors into your computer audio jacks.

One important point about softphones is that they have really gained popularity only since the widespread availability of broadband Internet access. PC to Phone software was available for dial-up connections, but it was often disappointing to use. The slow 56K bitrate combined with earlier computers that had slow processors and limited memory often resulted in poor audio quality and breakups in the conversation. You'll want at least 128 Kbps upload and download speed, even though some codecs may work at lower rates. That's especially true if you are going to use your computer as a computer while it is also being a telephone.

What's Spooking The ILECs

It's Christmas in March for the ILECs, the Incumbent Local Exchange Carriers. These are the phone companies that have squatting rights on local phone service, mostly because they are the children of Ma Bell. So, what did they get for Christmas from FCC Santa? They get to keep most of their toys and not have to share them with those pesky new kids, the CLECs or Competitive Local Exchange Carriers. What they really wanted was to go back to being the only children. But the other kids get to stay in the neighborhood. Worse yet, those other kids just might be getting new and better toys!

Here's what's happened. As part of the ongoing deregulation of the telecommunication business, the government has been moving toward a free marketplace where everybody can compete with everybody else. First, competitors were allowed into the long distance business to go up against AT&T. In 1996, competitors were let into the local phone markets.

To make this happen quickly, local phone companies were required to share their facilities with new competitors. They had to lease both the local phone lines and the switching facilities in a package called UNE-P or Unbundled Network Elements - Platform. Competitors could then offer long distance service through their own networks, combined with local service obtained by leasing the UNE-P service from the local phone company, and bundle them together for one low price. This is what made the local and long distance package plans take off. What really made it work was that the ILECs had to sell their platforms at the wholesale rate and not gouge their competitors.

Perhaps that sounds a little unfair to the locals, but in return they got the opportunity to enter the long distance markets and offer their own bundles of local and long distance service. They also retained the advantage of owning the copper. In other words, the actual phone lines that run to your house or business were installed over the last century by the local phone companies. They own them. During all those years, nobody else was allowed to string phone wires. Now there's so much wire in the ground and overhead that it would be too costly to duplicate. If you want service from a competitive local phone company, you first have to get it installed by the ILEC and only then can you switch to your preferred provider.

Now here comes Christmas in March. As of March 11, the ILECs no longer have to sell their UNE-P facilities for wholesale rates. They can, and have, bumped up the prices. In a year, those CLECs will have to get their own equipment or get out of the business. The only contested item will be the copper phone lines. You can still lease them from the local phone company in a new package called UNE-L or Unbundled Network Elements - Line.

Let's see. The local phone companies have taken back sole use of most of their facilities plus added long distance service to their offerings. Is Ma Bell being reincarnated? The local telcos must be jumping for joy. Or are they?

Ma or no Ma, those other kids aren't leaving the neighborhood. Some CLECs have already started co-locating their own switching equipment in the big local phone offices where there are thousands and thousands of lines to fight over. Others may merge, get out of the business, or compete in a different way.

Something that's really spooking the ILECs is that there are other wires besides theirs coming into houses and businesses. Cable TV was never a threat to the telephone companies until Cable started offering broadband. Now you can get VoIP phone service with an analog telephone adaptor called an ATA plus your Cable Modem service or DSL. Even if the local phone company owns the phone wire that carries your DSL, you could be bypassing them for your pricey long distance calls using VoIP over DSL.

The other wire that comes into just about every building is the electrical power line. BPL or Broadband over Power Line service has been approved and is up and running in some areas. If it spreads to more communities, VoIP over BPL could take the place of using telephone wires from ILECs.

Wireless is even scarier. Many high school and college students got their first phone as a cell phone and see no reason not to use it exclusively. Wireless Internet service is available in many areas now and WiMAX will be here in a couple of years. Voice over WiFi is starting to be an option in WiFi hotspots. What's going to happen when WiMAX expands the hotspot to 31 miles of coverage in all directions?

Then there is glass. We were taught in science class that glass doesn't conduct electricity so nobody expected that you could connect phones with it. Yet, fiber optic carriers do just that. A pair of copper wires carries one phone call or perhaps 24 if you use it for digital T1 phone service. A fiber optic bundle the same size can carry thousands and thousands of phone calls or the equivalent bandwidth of computer data.

This is the problem for the legacy phone companies. The advance of technology has so changed the options for delivering voice and data services that there is no going back to monopolizing the phone business. Not even if you could hog all the old equipment. Newer players will simply go wireless, fiber, cable, power line or some other technology that isn't out of the lab yet.

Telephone's Undertaker

Proponents of VoIP (Voice over Internet Protocol) have long been predicting the ultimate demise of the PSTN or Public Switched Telephone Network. Is it possible that the direct dial telephone system we've grown accustomed to over the last century is going to die out in favor of packet based digital telephony? If so, it would be appropriate to have an undertaker at the end. After all, it was an undertaker who was there at the beginning to make it all happen.

Most people believe that Alexander Graham Bell invented the telephone system. Bell actually invented the telephone, and by the narrowest of margins at that. He slid into the patent office a mere 2 hours ahead of his major rival, Elisha Gray. But that's another story.

The modern telephone switching network has its roots in Kansas City, Missouri just before the turn of the century. Bell's 1876 invention was widely in use by then. The original phone system was wired directly from phone to phone with a pair of wires. Sometimes only one wire was used and part of the run might have been barbed wire fence. The Earth would substitute for the other wire, but didn't work all that well over any distance. By 1888, the phone system had advanced to using switchboard operators to connect calls instead of running multiple wire pairs to every phone.

The switchboard worked well for most phone customers, but not for Almon Strowger. As the story goes, this Civil War veteran had moved to Kansas City and become a very successful undertaker. In fact, he was splitting the growing funeral market with only one other undertaker in town. Then business inexplicably started, shall we say, dying off. With a growing population there was no good reason for this. Was competition increasing? No, there were still only two undertakers, but Strowger's competitor was suddenly getting the majority of business.

Almon Strowger soon figured out why his once booming business was withering. His phone wasn't ringing much anymore because any callers who simply asked the operator to connect them to an undertaker were put through to his competitor. Why? The switchboard operator just happened to be the wife of said competitor.

Strowger was fuming. Being something of a tinkerer, he determined to put that operator out of business. But how? By building on existing electromechanical technology, he created a scheme where phone customers would push buttons on their telephones to make the calls themselves. A key invention is his two direction stepping relay now known as the Strowger Switch. The first version was built into a hat box. Banks of these switches detected the dialing pulses coming from the calling party's phone moved sets of wiper contacts horizontally and vertically to select one of a hundred possible connections. Strowger patented his invention on March 10, 1891.

Live phone calls looked to be more lucrative than the dearly departed, so Almon Strowger enlisted the help of his nephew William to form a telephone equipment company and open the first automatic exchange in La Porte, Indiana in November of 1892. His company, the Strowger Automatic Electric Company, later became Automatic Electric and supplied his switches to Bell Telephone. Strowger's push button phone was soon replaced by a rotary dial until it, too, was replaced by buttons again when DTMF (Dual Tone Multi-Frequency) or touchtones were introduced to support electronic switching systems. The Strowger or Step by Step switching offices were common throughout the 20th century.

For the latest and best pricing on local and long distance services, including VoIP, visit Long Distance Rate Finder .com.

The Biggest Communications Bird Is Up

The first in the constellation of Inmarsat I-4 communications satellites has been successfully launched into its geosynchronous orbit to serve the eastern hemisphere. A second I-4 will be launched later this year to provide coverage for the western hemisphere. Only 2 satellites will provide broadband voice and data coverage for the entire Earth. The third member of the constellation is a spare which is only needed for backup.

Thus continues an almost half-century of relay stations in space. The very first true communications satellite was actually a passenger on a missile test. In the dawn of the space age, the ATLAS ICBM was being readied as a space launch vehicle. In a few years it would take John Glenn into history as the first American to orbit the Earth. But on December 18, 1958 the mission was simply to place the Atlas B missile into low Earth orbit and make a statement to the world. The Army was asked to design a communications satellite that would be part of the missile and could relay messages for a couple of weeks. It was called Project SCORE for Signal Communication by Orbiting Relay Equipment.

The communications package for Project Score had two modes. The first is the familiar electronic repeater mode where transmissions from the Earth are amplified and retransmitted on another frequency. The second is a "store and forward" mode using tape recorders. The message from the ground is recorded while it is over the transmitting station. It is then played back over the receiving station, which might be on the other side of the Earth. A modern example of store and forward communications is voice mail.

The very first voice mail was a Christmas greeting by President Eisenhower. It was a last minute idea that made Project SCORE far more dramatic than the simple test messages that were originally planned. Tapes of the President's message were hurriedly uploaded to the fueled missile and recorded on the main and backup tape recorders. On December 19, 1958, President Eisenhower broadcast this message from space:

"This is the President of the United States speaking. Through the marvels of scientific advance, my voice is coming to you from a satellite traveling in outer space. My message is a simple one: Through this unique means I convey to you and all mankind America's wish for peace on Earth and goodwill toward men everywhere."

Before burning up in the atmosphere a month later, the 9,000 lb. rocket/satellite combination transmitted 78 voice and teletype messages by direct relay and store and forward.

The Inmarsat I-4 satellite alone weighs half again as much as the entire rocket and payload for Project Score. Ironically, it was launched by the latest version of the same Atlas rocket. Today's Atlas V is far larger and more powerful than the original ATLAS B ICBM, and includes strap-on solid booster rockets to aid in lifting massive payloads.

Besides size and sophistication, another difference between Project SCORE and Inmarsat I-4 is their orbits. Project SCORE was a low Earth orbiting or LEO satellite. Its orbit varied from 114 miles at the low point or perigee and 920 miles at the high point or apogee. One LEO satellite can relay messages around the world, but it needs that store and forward mode to do so. Otherwise you need a constellation of many satellites so that at least one is available to you at all times. An example of LEO satellites today is Iridium, which provides telephone service that is available anywhere through 66 low orbiting satellites.

The Inmarsat I-4, like most television and broadband data satellites, is parked in a geosynchronous orbit at an altitude of 22,223 miles. That distance is also called a Clarke Orbit after the author, Arthur C. Clarke, who proposed it in the 1940s before any satellites flew. The magic of that exact distance is that satellites orbit at the same rate as the Earth rotates so they stay in one point over the ground. Only 2 or 3 satellites will provide worldwide coverage in geosynchronous orbit. Dish antennas on the ground can be permanently pointed at them without any need for tracking.

Read more about the latest communications satellites in my article, "Broadband In Space."

Get connected with business grade broadband connections, including satellite, with a complimentary price and availability quote from T1 Rex.

Broadband In Space

Finding it hard to get broadband Internet service at your location? Look to the skies! More and more broadband services are beaming your way from above.

We normally think of broadband in terms of DSL, Cable Modem service, WiFi, Point to Multipoint Wireless, or T1 Dedicated Lines. In heavily populated areas, you may have your pick of these technologies. Your selection can be based on cost, speed, reliability and vendor preference. But what if nobody offers high speed data service in your area?

Satellite Internet and business data services are viable options today and will be even more so in the future. To see why, go outside and look up. What do you see? Nothing? That's it! The beauty of aiming an antenna upward is that there is nothing to get in the way. On the ground, there are all sorts of pesky trees, tall buildings, mountains, water towers and other obstructions to get in the way of wireless transmission. The curvature of the Earth comes into play over long distances, which is one reason why you can't beam microwaves from coast to coast, or even across state without relay towers. Satellites have no trouble with signals that have traveled 22,300 miles from the ground.

Of course all these obstructions don't faze wireline services such as DSL, T1, and Cable. Or do they? The cost of the cables is the cheap part of building out wired services. It's the cost of running the wires, hanging them from poles, burying them in the ground and the cost of getting a right of way to do so that adds up. In areas of low population density there may by nobody who wants to bear the expense of pulling cables or putting up a tower.

That's the attraction of space and near-space. Anyone in a satellite's footprint can get service if they have a clear view of the bird. It doesn't matter how many or how few other people are also pointing their dishes to the sky in the same area.

DIRECWAY is a popular consumer broadband satellite service. It costs $60 to $100 a month depending on how much you want to pay up front for the ground station equipment. For that you get download speeds up to 500 Kbps and upload speeds up to 50 Kbps. This asymmetrical upload/download bandwidth is suitable for Internet access such as email and web surfing.

MegaPath Satellite Service (MSAT) is oriented toward business users and can provide up to 1 Mbps down and 192 Kbps up. It also comes with a service level agreement guaranteeing 99% uptime. MSAT service is targeted to Internet access, point of sale terminals, credit card authorization, and so on.

Both of these satellite services fall into the category of VSAT or Very Small Aperture Terminal. That's typically a dish about 2 1/2 to 3 feet in diameter (1 meter) up to 2 or 3 times that size. These dishes easily mount on the roofs of homes, businesses and even vehicles.

VSAT equipment uses the C band (4/6 GHz) or the Ku band (12/14 GHz), with the smaller dishes using satellites on the Ku band that is shared with digital satellite TV. The next move is to the Ka band at almost twice the frequency (20/30 GHz). Internet service using the Canadian Anik F2 satellite will be available later this year from WildBlue Communications. The Ka band offers wider bandwidths but the higher frequencies are more easily blocked by rain.

Inmarsat is launching a constellation of three I-4 satellites this year that will cover the globe with over 200 spot beams each. These are the largest communications satellites to date, weighing in at over 13,000 lbs. They'll operate in the C band and L band (1/2 GHz) to provide data speeds up to 432 Kbps. This Broadband Global Area Network (BGAN) will serve land based stations, aircraft and ships.

Of course, you don't really need to go all the way into space to get the advantages of overhead transmission. The Sanswire Stratellites, automated blimps acting as Wireless Internet Service Providers, will hover in the stratosphere at 65,000 feet with coverage of cities, counties and even states. You can read more about this technology in my article, "Your Next ISP Is a Blimp."

Generalized MPLS Improves Optical Networks

MPLS or Multi-Protocol Label Switching is a technology that speeds up networks and carries a variety of protocols including IP, ATM, Frame Relay, and SONET. It does this by encapsulating them in its own tunnels as they enter the network and returns them to their original state when they leave. While they're on the MPLS network, they are routed according to simplified tags that are inserted into the packet headers.

Building this specialized network to carry other network traffic has an advantage of being able to define classes of service to ensure that real time data, like voice and video, gets the bandwidth and low latency it needs to function. The fact that this network is a multi-protocol network makes it especially attractive to carriers who need to transport anything and everything. Now a set of extensions called GMPLS or Generalized Multi-Protocol Label Switching adds even more versatility to an already accommodating network.

While MPLS is intended to control the flow of packets in a packet switched network, GMPLS recognizes that there are other types of networks with elements that are not necessarily packet oriented. For instance, TDM or time division multiplexing, the legacy digital telephony standard and the one used as the foundation of SONET (Synchronous Optical NETwork), is based on time slots not packets. Packets can be carried on TDM networks, but if they are too big they get split into multiple time slots and reassembled later. The advantage of having all of those nice, neat, predictable time slots is lost since they have no relevance in the packet switched world.

GMPLS puts TDM back to work. A time slot can be considered a label. There is no need to add more labels, since the network always knows what data is being carried on what time slot. Likewise, a wavelength or Lambda can be considered a label in a WDM or wavelength division multiplexed network. Even an entire fiber can be treated as a GMPLS label to define a path through the network.

Adding labels to everything the network can use in deciding how to route data packets gives the GMPLS network a lot of self-determination. It accepts data of many different protocols at the ingress point. It then adds its own labels which can be the MPLS "shim" type that are inserted in the packet headers or the "implicit" type that are associated with particular fibers, wavelengths, or TDM time slots. The GMPLS data is routed by the label routing switches over the predetermined paths decided at the ingress point. When packets reach the network edge, the egress point, all labeling information is removed and the various types of data go their separate ways in their native protocols.

Notice that there is no mention of manual intervention to provision circuits or set up routes. One of the advantages of GMPLS networks is that they know what network resources they have to work with and go about setting up and tearing down their label switched paths as needed. As GMPLS networks become widely deployed, it is expected that the laborious job of provisioning services will get much easier and faster because of all this automation.

You may also wish to read my article, "MPLS Networks Are Coming Your Way."

If you would like to find reliable high-bandwidth network services at attractive prices, try our GigaPackets optical networking quote service.

Channelized vs Unchannelized T1 Lines

A T1 line is a T1 line, right? Well, yes and no. T1 line service can be formatted in different ways to suit its intended application. What you would set up to serve your analog PBX system is likely different that what you want for dedicated Internet service.

First of all, there are certain characteristics of T1 lines that you'll always find. They are defined by standards that were originally created by AT&T and modernized by ANSI (American National Standards Institute). International standards are provided by the ITU (International Telecommunications Union).

A T1 line is a synchronous digital transmission running at 1.544 Mbps with certain signal characteristics. It is divided into frames of 192 data bits plus 1 framing bit for a total of 193 bits. There are 8,000 of these frames per second. That gives you 1.536 Megabits of data per second.

Now's where the various flavors of T1 come into play. Many companies use that 1.536 Mbps of bandwidth for what's called dedicated Internet service. The line is dedicated to Internet service and is not shared with other customers. It often is shared within the company by plugging it into a router that has a T1 CSU (Channel Service Unit) and using the router output to feed the corporate network.

Using a T1 line as a data pipe is also called "Unchannelized T1" because the 192 bits or 24 bytes per frame are not divided up further by the T1 line equipment.

Unchannelized T1 is a fairly recent development. When T1 or Trunk Level 1 was being put into service in the 1950s, it was designed to carry telephone traffic. Each call is separate and distinct, so the T1 frame was divided into 24 channels of 8 bits each. Running at 8 Kbps, that gives each channel a bandwidth of 64 Kbps or just right for one toll quality telephone call. Using a T1 line in this fashion is called "Channelized T1."

Channelized T1 is still popular today to provide multiple telephone lines to a PBX system. It replaces up to 24 separate pairs of telephone wires. A single T1 line combining all those phone lines into a single 4 wire line is often considerably less expensive that running them all separately. A PBX system with a T1 interface card will assign the channels as needed to support up to 24 simultaneous telephone calls.

For a PBX system or Key Telephone System that expects separate phone lines, a device called a "Channel Bank" will do the T1 multiplexing and demultiplexing and conversion between analog and digital formats. A typical channel bank has one connector for the T1 line input and 24 pairs of standard telephone lines as the output. The point is that whatever you connect to those phone lines doesn't know whether they came from the phone company as separate wires or were carried on the T1 line.

An excellent reference manual on the intricacies of T1 is "T1, A Survival Guide" by Matthew S. Gast and published by O'Reilly.

Let T1 Rex help you find the best prices on T1 channelized, T1 unchannelized and other T1 digital line services.

Why T1 Prices Have Tumbled

If your long term contract for T1 line service is expiring soon and you've checked recent prices online, you may be in for quite a shock. If not, take a second and see what our quote engine at T1 Rex comes up with. Go ahead, it will open in another window.

So how much cheaper are today's T1 prices? 25%, 33%, maybe 50%? What's THAT all about?

T1 or T-Carrier used to be one of those staid propietary digital line services that you only got through your local phone company. You probably didn't use T1 unless you needed it to support a call center, medium to large PBX system, Internet service for a corporation, or point to point private line. Now it seems like everybody is looking for T1 service.

There are two reasons for the T1 boom. First, even small and medium businesses are being driven to install digital lines to support their point of sale terminals, accounting systems, supply chain integration and online presence. Just today I stopped by a popular restaurant for a dish of frozen custard and noticed that they had hooked up an inexpensive wireless router and were providing free WiFi Internet service to their customers.

Very few businesses are too small or unsophisticated for an Internet connection anymore. The smallest will use an ADSL or sometimes a Cable modem service. Those services are really intended for consumers and are offered on a "best effort" basis. In other words, no service guarantees. A business that depends on its network to process credit cards, order supplies, and communicate with the home office will probably want at least a fractional T1 and likely a full T1 line.

So why are prices going down and not up with all the demand? First of all, the technology has been improved. The original T1 transmission scheme was implemented in the 1950s and was intended for internal use between phone company offices to carry phone calls in bulk. This is also called trunking. When it was made available to businesses, the installation costs were high because the copper pairs used must be carefully chosen and regenerators must be installed if the span is over 6,000 feet. Only a single T1 circuit could typically be provisioned in a 50 pair wire bundle because the T1 signals would cross-talk or interfere with each other.

That's all changed in the last ten or fifteen years. A new line coding scheme called HDSL (High Speed Digital Subscriber Line) is far more forgiving of minor defects on the two pair of unshielded copper wires it uses and doesn't need signal regeneration until it reaches 12,000 feet from the phone company office. Don't let the DSL in HDSL fool you. This is a guaranteed service that provides the same T1 interface at the customer premises as legacy T1. Only the modulation scheme has been updated to more modern standards. An even newer standard, HDSL2, provides T1 service using only a single copper pair. That's basically a standard phone line. When HDSL2 is available, T1 service can be provisioned more quickly and easily, and thus more cheaply, than ever before.

The other big change in the cost structure has come from competitive carriers entering the marketplace as the result of deregulation in the telecommunications industry. A few years ago, you might have had one place to go for T1 service and they knew it and priced accordingly. Now, you might get a dozen options through a telecom broker like the one we work with. There are many competitive digital line service companies vying for your business. Competition has brought lower prices. Note that the actual installation may be handled by the local phone company because they own the copper phone lines by law. However, the actual voice or data service and any long distance private line service can be provided by competitive carriers, also called CLECs.

So are T1 prices likely to continue falling? Probably not indefinitely. As business conditions improve, excess capacity in the telecom industry is going to get used up. Supply and demand may well cause prices to rise at some point rather than continue to fall. That's something to consider when deciding whether to lock in the current low rates on a one, two or three year contract. You should also know that higher rate digital services, such as DS3, OC3, and Ethernet have seen price reductions similar to T1. This is part of what is enabling enterprise level VoIP as a cost reduction measure.

Whatever your bandwidth needs, don't renew your contract until you check your options. Visit T1 Rex and use our free quote service now.

How Bluetooth Cuts The Cord

Bluetooth is a quaint sounding wireless networking standard that solves the problem of last-inch connectivity. Let's face it, there are lots of standards for last-mile connectivity including DSL, Cable Modem Internet, PON (Passive Optical Networks), T1, BPL (Broadband over Power Line), and even WiFi. Well, WiFi is really more of a last-foot connectivity solution designed to eliminate Ethernet wiring within a home or office. Bluetooth is more likely to eliminate USB and parallel printer cables within a room. It also eliminates other short wires, such as the tiny but annoying cable that links a headset to a cellular phone.

But why call it Bluetooth? It's not a joke and it's not just because engineers got tired of those arcane acronyms like USB and IrDA. No, the serious reason is that it was named after a Danish king who united Denmark and Norway just before the turn of the first millennium. His name translated into English sounds like "blue tooth." Symbolically, the Bluetooth communications standard unites disparate devices like cell phones and computers.

If that's not quaint enough for you, consider that one of the primary technologies behind the Bluetooth transmission standard is FHSS or Frequency Hopping Spread Spectrum, based on a patent issued to a stunning 1930's film actress and a noted music composer who were trying to invent a secret military radio control system for torpedoes. I'm serious. I relate that story in "Thank Hedy Lamarr for Bluetooth."

Moving right along to the Bluetooth protocol itself... This is a very low power wireless networking scheme that draws as little as a milliwatt and has a maximum range of about 32 feet. That's more than enough range for a keyboard, mouse, desktop printer, PDA, laptop computer or cell phone. All of these devices could theoretically link together via Bluetooth. By keeping the power low, the component size is small and the battery consumption is low. That's just what you want in a cord replacement.

Bluetooth really is a networking standard. Instead of a LAN or Local Area Network, it's a PAN or Personal Area Network. Bluetooth devices establish what are known as piconets. A piconet contains a minimum of two devices and a maximum of 8. No manual intervention is needed. The process of setting up the network is completely automatic when Bluetooth enabled devices are within range of each other. One device assumes the role of the master and invites other nearby Bluetooth enabled devices to join the net as slaves. Once all 8 available slots are filled, no other device can join. The master and the slaves take turns communicating in a round-robin scheme. Communications between slaves must be sent via the master and not directly.

All of this is going on at a data rate of 1 Mbps for the standard Bluetooth and up to 3 Mbps for Bluetooth version 2.0. They are compatible standards and run at a speed that the slowest device in the piconet can keep up with. Deducting overhead in the transmission protocol, the basic communications rate is around 720 Kbps. There are options including half-duplex, full duplex, asynchronous connectionless and synchronous connection oriented links. The data bits can be information, digital control words or even two-way audio at 64Kbps. That's perfect for telephone applications, as 64Kbps is the legacy standard for toll quality digitized voice.

Bluetooth operates smack in the middle of the unlicensed 2.4 GHz ISM (Industrial, Scientific and Medical) band. If that has a familiar ring, it's because WiFi uses the same frequencies. What keeps them from clashing is different modulation schemes. Bluetooth deliberately picked a frequency hopping scheme to avoid interfering or being interfered with. It switches randomly among 79 channels at a rate of 1,600 times per second. Only devices on a particular piconet are synchronized to hop to the same frequencies at the same time. This greatly reduces the chances of noise or other transmitters blocking out the entire data stream. If bits are lost on once channel, they can be resent on another.

What are typical uses for Bluetooth? A popular application is wireless headsets for cell phones. If your phone has Internet capability, a Bluetooth piconet can be established between your phone and nearby laptop computer to give the computer Internet access as well. Bluetooth enabled printers can print pictures from a cell phone or camera that has Bluetooth without needing any wires. Likewise, a Bluetooth enabled PDA can synchronize with a Bluetooth enabled cell phone, laptop or desktop computer. As devices that meet the 2.0 standard become more commonly available, the higher throughput will be used for wireless audio components and appliances as well. It seems likely that Bluetooth will replace infrared links that need direct line of site and perhaps the bulk of interface cables we're so accustomed to.

Find Bluetooth enabled cell phones and cellular service plans at Cell Phone Plans Finder.

Thank Hedy Lamarr For Bluetooth

The next time you are using your wireless cell phone headset or synchronizing your PDA, be aware that one of the key technologies in Bluetooth enabled wireless devices was co-invented by a beautiful and famous 1930's film actress.

I first ran across this amazing story in the Spring, 1997 edition of American Heritage of Invention & Technology Magazine. In fact, the cover boldly proclaimed "Hedy Lamarr, Munitions Inventor." Munitions? Bluetooth? Movie actress? What sort of bizarre tale is this?

The story begins on the eve of World War II. Hedy Lamarr, the former Hedwig Eva Maria Kiesler, was married to Fritz Mandl, a preeminent Austrian arms manufacturer. She divorced Mandl in 1937 and moved to Hollywood where Louis B. Mayer of MGM gave her the name Lamarr. What she learn while married to Mandl apparently stayed on her mind, though. In 1940 she struck up a conversation with her neighbor, a noted music composer. Hedy had an idea for radio controlling torpedoes by constantly moving the control frequency so the radio signal wouldn't be detectable or easily interfered with. What she needed was some practical way to make it work.

This is where George Antheil, her neighbor and composer, thought it might be done like a player piano. Why not? A player piano roll causes a constant set of frequency shifts by changing notes to play a song. If you synchronize two identical piano rolls, one at the transmitter and one at the receiver, you can change transmission channels at will. The transmitter roll switches a different capacitor in the oscillator circuit to change frequency and the receiver roll does likewise to retune the receiver. Anyone else trying to tune in this signal will only catch it for a moment before it changes. The eavesdropper doesn't know what frequency is next on the roll, so he doesn't know where to tune next.

George Antheil and Hedy Lamarr, by then remarried with the name Hedy Kiesler Markey, are the two inventors named on the 1942 patent called "Secret Communication System." It's patent number 2,292,387 if you want to get a copy. The Navy didn't jump on the idea, thinking the piano roll scheme was too hard to get working reliably. In 1957, engineers at Sylvania redesigned the scheme using electronics and it became the basis for secure military communications.

So what's this got to do with Bluetooth? You might recognize the methodology by its current name: Frequency Hopping Spread Spectrum or FHSS. The twin characteristics of FHSS are secure transmissions and interference resistance. Interfering signals might drown out one of the frequencies in the hop sequence, but any data lost during that brief outage can be resent on another frequency. That's a good characteristic to have for low power data communications on the crowded 2.4GHz band shared with WiFi.

The Bluetooth transmission protocol uses a set of frequencies between 2.40 and 2.48 Gigahertz. It selects from among 79 frequencies and chooses a new one 1600 times a second. That would be tough to do with piano rolls, but the implementation in integrated circuits still follows the basic patent awarded to a music composer and a movie actress. Thanks Hedy! Thanks George!

If you can't find the Spring, 1997 issue of Invention & Technology, you can read a similar account of Hedy Lamarr's story at Radio-Electronics.com.

Learn more about Bluetooth communications at The Official Bluetooth Wireless Info Site

How The International Business Traveler Stays Connected

Heading overseas on a business trip or vacation? Working abroad? Giving your high school or college student the opportunity to live and study in a foreign culture? You have the luggage, the tickets, the passport. But are you ready to communicate?

No, I don't mean carrying around a phrase book or one of those electronic translators. I mean how do you stay connected with home or the home office? Have you given it any thought or just figure you'll use whatever facilities they have in the hotel? Ouch! That stabbing pain is coming from you wallet and its hemorrhaging money.

If you need a passport to get where you're going, you should also be making plans for how you'll stay in touch. Internet facilities may be non-existent, hard to find or very expensive. Ditto for standard telephone service, although you'll probably be able to place a phone call at some price just about anywhere. Figuring you'll just flip open your cell phone and call as usual? Oops. It doesn't even work.

A better plan is to control your costs up front. Take your voice and data services with you and use the local facilities only to connect to a toll free or local access number.

Can you take your cell phone along? You can if you are a T-Mobile subscriber and you have a "world phone" that works on the international GSM (Global System for Mobile communications) bands. You'll need a dual band or triple band cell phone for this. The USA cellular band phones don't operate overseas and vice-versa. You also need to activate the T-Mobile "WorldClass" service before you leave to have global roaming on your cell phone.

Otherwise, if you have your heart set on using a cell phone outside your home country, your best bets are to get your service locally. Sign up for cellular service in the country where you'll be staying if you are going to be there for a year or more. If it's just a short trip, you'll be better off renting. Be forewarned, though, these are not necessarily your lowest cost options.

For telephone calls far away from home, it's hard to beat the billable international calling card. The per minute rates are low, they work to and from most places you are likely to be, there are no minutes to run out and leave you stranded, and you don't pay anything just for having the card or virtual card in you wallet. Your credit card is billed for the calls you make.

By the way, a virtual calling card is just like a regular calling card, sans plastic. You get an account number, PIN, and dialing instructions via email when you sign up for service. You keep this info in a safe place for when you need it. An advantage to this type of service is that you can generally get it ready to use within one business day since there is no physical card to send through the mail. Perfect if you forget to make arrangements until the last minute. A very popular virtual international calling card service is provided by CogniCall. A more traditional plastic card is available from AccuGlobe.

Now that you have your international communications plans set, there's only one more thing to say: Bon Voyage!