Friday, March 24, 2006

Dynamic T1 Lines offer Voice and Data Integration

T1 lines are digital trunks that can carry voice, data or both. The traditional T1 line is configured as 24 channels of 64 Kbytes each for a total of 1.5 Mbps bandwidth. Each channel carries one digitized telephone call. Since the channels are pre-configured, if you have only 12 telephone lines in use, the other 12 are simply idle. In some cases, the line is set up to be 23 telephone calls plus 1 data channel to carry information such as Caller ID and signaling. This is called a T1 PRI or Primary Rate Interface. The biggest application for T1 voice lines is to support PBX telephone systems and call centers.

A T1 line can also be configured as one big data pipe instead of 24 individual channels. Unchannelized T1 lines are often used to provide dedicated Internet access with 1.5 Mbps bandwidth. Another application is point to point private data transmission between business locations.

If you need both telephone and Internet or data exchange service, there are several ways to accomplish this. One is to buy separate T1 lines, each set up for a particular purpose. A T1 voice line would service the telephone system. A separate T1 data line would provide Internet service for the business. In larger businesses, it is possible that more than 24 phone conversations would be going on concurrently. In that case, multiple T1 lines would be used for the voice application. T1 data lines can be bonded to incrementally increase bandwidth to 3, 4,5, 6, 9 or more Mbps.

Small and medium size businesses may not need a full T1 line for telephone service and another full T1 line for Internet access. Integrated T1 service combines voice and data on to a single T1 connection. A static setup allocates a certain number of channels to voice and the rest to data. A typical arrangement is 12 phone lines plus 768 Kbps of Internet data over the remaining bandwidth. Many businesses can get by with a single T1 line serving all their telecom needs.

A newer and more flexible arrangement is Dynamic T1 line service. A dynamic T1 line may be channelized, but the channels will be assigned as needed. If there are no phone calls in progress, the entire bandwidth is used for data. As soon as someone pick up a handset, one channel of 64 Kbps is dedicated to that call and data bandwidth is reduced by 64 Kbps.

Another technical approach gets rid of the channelization completely and sends everything as data packets over the T1 line. Internet data is already packetized, so the telephone calls must be converted from analog or TDM (Time Division Multiplexing) digital to VoIP packets at each end of the line. The beauty of this approach is that bandwidth can be allocated on the fly packet by packet, making optimum use of the available bandwidth. The process is known as dynamic bandwidth allocation.

To ensure voice quality, the voice packets are given priority over the data packets. Email and Web traffic, even data downloads, aren't much affected by short delays, also called latency. A data packet can wait for a voice packet. Voice is a continuous stream and will become distorted or drop out if the latency delays get too long. The other quality control comes from the dedicated T1 line from customer to carrier. The carrier installs a IAD or Integrated Access Device at the customer location to handle the conversions, and telephone gateways and routers at the carrier end. This arrangement can guarantee sufficient bandwidth to ensure toll quality telephone calls.

Note that even though dynamic bandwidth allocation is based on packet switched technology, you don't necessarily need VoIP telephones to take advantage of this service. The IAD provides analog phone lines or a T1 telephone interface to your PBX or Key Telephone System, plus a WAN data port for your Internet router. You can use the equipment you already have. If you have already installed an enterprise VoIP phone system, you can also take advantage of dynamic bandwidth allocation without the need for conversions to TDM or analog standards.

Is Integrated T1 or Dynamic T1 service right for your business? The best way to find out is to let our Shop For T1 technical consultants review your needs and recommend options that will give you the service you want at the best possible price. Just enter some basic information on our real-time quote engine at T1 Rex and a consultant will be in touch by phone or email at your convenience.

Click to check pricing and features or get support from a Telarus product specialist.

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