T1 Voice Options for Call Quality

Any business who's telephone communications are the lifeblood of its operation can settle for no less than excellent call quality at all times. That includes natural sounding voices with minimal noise and distortion. Calls that break up or are dropped are unacceptable. So are echo chambers and that annoying speech clipping that makes it sound like you're using walkie-talkies. If you don't want that, what you do want is T1 voice service.

T1 lines are a natural for business telephone systems because they were designed for telephony from the ground up. T-Carrier, the technology that includes T1 (1.5 Mbps) and T3 (45 Mbps), was invented for use by the phone companies themselves. It replaced the web of wires and poles that carried phone calls from telco office to office with a highly efficient digital system.

Quality of Service (QoS) is inherent in the nature of T1 technology. The line is divided into 24 separate channels, each assigned its own time sequence in the bitstream. This is what's known as TDM or Time Division Multiplexing. TDM requires precise synchronization at both ends of the transmission. Atomic clocks and the stability of today's solid state equipment makes this a well established and robust process. Because the channels are unique and completely separate, one call cannot interfere with another.

Latency is also not a problem with T1 telephone lines. The precise timing required for channel synchronization keeps the bits moving along at a steady rate. In IP networks, packets can be inspected and delayed along the way and still retain their integrity. T1 voice channels must maintain their place in line. Unlike most packet networks, T1 voice channels don't share the network bandwidth with other types of data that can cause congestion problems. When there is no phone call in progress on a particular channel, it idles while maintaining synchronization with the other channels.

Voice tonal quality is set by the CODEC or Coder/Decoder that converts between the analog signals in the telephone handset and the digital format used for transmission. Each T1 channel is 64 Kbps, organized as 8 bits at 8 Kbps using the industry standard G.711 CODEC. This standard is called "toll quality" and was chosen to mimic the analog phone spectrum that existed prior to digital transmission.

If you are happy with the sound of your telephone system in-house and want to maintain that quality between company locations or between your contact center and your customers, T1 phone lines offer a proven and robust solution. A popular option to the standard T1 voice line is T1 PRI or ISDN PRI. PRI stands for Primary Rate Interface, and ISDN term. PRI uses the same standards as T1 but reserves one channel exclusively for signaling, control and information. You have 23 vs 24 telephone channels per T1 PRI line but call connection times are faster and you can get Caller ID or ANI information delivered to your PBX system.

T1 telephone lines have the built-in mechanisms to maintain voice quality for consistently excellent telephone calls. They are also readily available at lower lease costs than ever before, including historically low per-minute rates. Check prices and availability of T1 and T1 PRI telephone lines for your business application now and have the call quality you really need.

More Mbps, Less Money

The need for more and more business bandwidth is bumping up against the need for larger and larger cost savings. On the surface, it would seem an impossible situation. But look closer and there may be a way to meet both network performance and budgetary constraints.

There are really two approaches to optimizing bandwidth economics with little or no up-front investment. Both work and they are not mutually exclusive.

The first is strictly competitive. Telecommunication line contracts are based on monthly lease commitments for 1, 2 or 3 years. During the course of the contract term, the competitive landscape can change dramatically. What cost $1,000 a few years ago might be had for $500 or less today. That scales all the way from T1 voice and data lines up to optical carrier services. Can you save 25 to 50% or more by simply switching vendors? It's done everyday. The most dramatic savings are seen in areas that have only recently seen competitive carriers move in or in situations where contracts have been automatically renewed over and over with little or no price negotiation.

The second approach is to switch technologies. That may seem like a daunting prospect. After all, you've spend a lot of time stabilizing your network. The last thing you need is to throw some technical incompatibility into the mix.

But transport technologies are more compatible than you might think. Most network traffic today is based on packets. Ethernet packets to be precise. Older metropolitan and long haul networks were developed around telephone technology and based on digitized voice channels. There's no reason that a T1 or OC3 connection can't transport packets instead of voice streams. You've been able to get T1 and SONET data lines for years. To make this work, there is circuitry that performs a protocol conversion so that packet data can be sent as collections of bits the right size for the line technology and then reassembled at the other end.

All of this conversion from one network protocol to another happens transparently and so fast that you are unaware of it as a user. You know that you have a dedicated connection to the Internet or a private data pipe from point to point. How it all works is unimportant. Or is it?

A network designed from the ground up to be compatible with the core protocol that you are running is bound to have less overhead and be more efficient. That's the idea behind IP core networks and Carrier Ethernet. Competitive carriers without a legacy investment in telephony networks have been building out all-new IP networks serving regional areas and even the entire country. This is where you'll find Ethernet services for metro and long haul applications.

But does switching to Ethernet from TDM technologies like T1, DS3 and OCx really save anything. In many cases, yes. No, you won't be able to get a 10 Mbps Ethernet service for the same price as a traditional T1 line, but the cost per Mbps might be 1/3. It gets even more dramatic when you move up to 100 Mbps Fast Ethernet and 1000 Mbps Gigabit Ethernet. Depending on your location, Fast Ethernet even get you twice the bandwidth for less money overall than a standard DS3 service.

A third approach is to add hardware based bandwidth optimization to squeeze the most out of the lines you have. This is more of a trade-off arrangement versus an outright cost savings. There's a cost for the WAN optimization appliances that needs to be offset by the costs avoided by not upgrading to faster connections. If you are in a situation where it would be really expensive to move up the next bandwidth increment due to limited service choices, bandwidth optimization can buy you the breathing room you need for your business activities.

PRI vs POTS Telephone Service

Business telephone systems range in size from single line desk phones through enterprise telephony with hundreds or thousands of handsets. Chances are that your business needs are somewhere in the middle. But where? What is the right service for you?

The most basic and traditional phone service is called POTS or Plain Old Telephone Service. Chances are that you won't see it advertised that way. Instead it will be called business line or dial tone service. What you get is an analog connection to the nearest telephone company Central Office or CO. Any conventional telephone will plug into the RJ11 jack on the wall and give you dial-tone when you lift the handset. You can expand the number of rooms with phones by paralleling twisted pair wiring to other phone jacks. But you still only have one line and, if it is in use, no one else can make or receive calls.

Basic POTS is local phone service. Long distance service is either bundled for a single price or assigned to a competitive long distance carrier that offers lower per-minute rates on separate billing. Caller ID is an add-on service that is multiplexed on the same phone line and displays the caller's phone number and other information on phones with the necessary display, or a separate Caller ID unit. Toll free service can be added to forward incoming calls from a toll-free number to your phone line.

A logical upgrade from POTS is to add a separate identical line service and use a two-line business phone. These are commonly sold in office supply stores and can work well for small offices. Such phones are entry level Key Telephone Systems. What distinguishes a key system is that there are buttons or "keys" on each telephone to select the desired phone line. These buttons flash to indicate the line is ringing with an incoming call or light steadily to show that line is in use. Larger key systems can handle a half-dozen separate phone lines.

Businesses with 6 or more outside lines are likely to switch to a PBX or Private Branch eXchange phone system. Like the name implies, this is a mini telephone company office on your premises. Once giant racks full of equipment, the modern PBX may be just a small box that sits on a shelf in the telephone closet. PBX systems work differently from Key systems. The PBX manages all the phone lines for incoming and outgoing calls. It also interconnects all the telephone handsets so you can dial from phone to phone inside your building without incurring any telephone line charges. When you need to make an outside call, the PBX system will assign you the next available line. You don't really need to know which one it is, they all work the same. Callers can directly dial a number for your phone, called DID, or reach an automated system where they can enter your extension number. The PBX will then ring your phone.

Up till now the phone lines we've been discussing for all of these different telephone systems are individual analog POTS lines. You pay for each one separately and the total cost is generally the cost per line time the number of lines. Once you need 8 to 12 lines or more, it usually makes economic sense to switch to digital trunk rather than use multiple analog lines.

The digital trunk, called a T1 voice line, converts up to 24 separate phone lines into a single digital connection between you and your phone service provider. The most popular variety of T1 service is called T1 PRI or Primary Rate Interface. It is also known as ISDN PRI for Integrated Services Digital Network. The difference between a T1 PRI line and a T1 voice line is that the PRI protocol establishes one channel of the 24 as a switching and data channel. This makes calling faster and allows you to have Caller ID for the other 1-23 channels or 1 to 23 outside phone lines.

If your phone system has grown over the years to a dozen or two dozen analog phone lines, it's time you got a competitive quote for T1 PRI lines service. Connecting PRI to your PBX system usually involves plugging-in a special interface card if your system doesn't already have one. Many new PBX systems come with this connection feature.