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.
