Thursday, April 16, 2009

T-1 Digital Telephone Lines

If your business has multiple telephone lines, you may already be familiar with T-1 digital telephone lines. If not, you may be missing an opportunity to save money on every monthly phone bill. Even if you have T1 service installed now, you may not be aware of all the currently available options and the cost savings that could be yours.

Digital telephony traces its roots back to the 1950's, when the telephone companies were looking for ways to efficiently transport dozens, even hundreds or thousands of phone calls. Basic analog phone lines carry only one conversation per pair of copper wires. An analog multiplexing scheme, called carrier telephony, treated the phone lines like radio bands to transport multiple calls per pair of wires between phone company offices. Multiplexed analog trunks cut down of the number of wires needed, but suffered from noise and crosstalk problems that lowered long distance call quality.

The T-carrier system, which offered T1 and T3 digital trunk lines, has been the solution of choice for both telephone companies and larger businesses for decades. T1 lines are divided into 24 time multiplexed channels, each carrying one digitized telephone conversation. Only two pair of common telephone wire are needed for T1 telephone line. One pair is for transmit and one for receive. T1 lines start making economic sense when you have 10 or 12 outgoing phone lines. That threshold is shrinking as T1 line prices are steadily reduced, while analog phone line prices remain relatively constant.

An improved T-1 digital telephone line is called ISDN PRI, short for Integrated Services Digital Network Primary Rate Interface. It's called PRI or T1 PRI for short. PRI uses a channelized T1 line but reserves 1 of the 24 channels for signaling and digital information. The other 23 channels are available to support telephone calls. This technology has the advantage that all of the bits in each channel are used for digitized voice signals. The signaling channel serves the other 23 and makes calls connect and disconnect faster. It also provides Caller ID information, which standard T1 phone lines cannot support. T1 PRI is now the standard for business PBX systems and call centers, where multiple phone lines are in simultaneous use.

But what if you only need 4 to 6 outgoing phone lines? There is another solution called Integrated T1 service that combines telephone and Internet service on a single T1 line. You get up to 12 channels for telephone service. The rest are used to bring in broadband Internet access. A version called a dynamic T1 line automatically reassigns unused telephone channels for Internet bandwidth until they are needed. This way you can get up to 1.5 Mbps broadband speeds for upload and download but be sure that phone service is always given priority as needed. The cost of Integrated T1 service is attractive because most companies need both telephone and Internet service.

An even newer T1 line service is called SIP Trunking. SIP is the signaling protocol used by VoIP telephone systems. A SIP Trunking provider offers both VoIP telephone service and Internet access over a single T1 line. If you need more capacity on this or any of the other T1 services, you can add additional T1 lines as needed.

Are you interested in exploring the cost savings opportunities offered by T-1 digital telephone lines, or looking to see if you can save money on your current digital services, then use our Shop For T1 GeoQuote (tm) search tool to get instant online quotes so you can compare prices.

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

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