My earlier writing omitted mention of E-1. I have written a few paragraphs to try to remedy it. Would the interested persons please have a look at it and criticize, especially folks familiar with E1.
Gene Naden, MA Programmer Analyst GlobalTeldata II, LLC 4700 N. Ravenswood Chicago, IL 60640 (773) 878-3161 x 223
T-1 AND E-1 In the context of Asterisk, T-1 and E-1 are digital telephony schemes that multiplex a number of voice channels onto one line. E-1 is used mainly in Europe and Asia, while T-1 is used in the United States and Canada. In either case, signaling and framing information must be carried, either within the voice channels or in separate, non-voice channels. There are various signallng and framing schemes. One signaling scheme that is used with Asterisk for T-1 connections is ISDN PRI (Integrated Services Digital Network, Primary Rate Interface.) With IDSN PRI, a T-1 connection has 24 channels. In the context of Asterisk, channels 1-23 carry voice and are referred to as "B" (bearer) channels. Channel 24 carries signaling information and is referred to as a "D" (data) channel. ISDN PRI signaling is also used for E-1 connections. Such an E-1 connection has 31 channels. For Asterisk, channels 1-15 and 17-31 carry voice and are called "B" channels, while channel 16 carries signaling information and is called the "D" channel. Channel zero is used for framing.
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