lml,
>>What are ISDN BRI & 2B1Q extenders? Is this what I have on my line?<<
Yes, very likely. Extenders are just another way to say repeaters or line boosters.
BRI stands for Basic Rate Interface and consists of 2 Bearer channels for either or both data and voice, each at 64 kbps, and one lower speed Delta channel, typically rated at 16 kbps, for ancillary and supervisory signalling. Together these add up to 144 kbps of "apparent" signalling. Sometimes, depending on the configuration of the delivery system, the "actual" transmission rate is higher than 144, but the usable portion is still only 144 kbps.
2B1Q is the line format that is most often used to deliver the BRI signal to the end user location, and it stands for 2 Binary 1 Quaternary encoding.
From: shiva.com :
"The current standard is the American National Standards Institute (ANSI) 2B1Q line code. The line code groups two bits together and codes them in voltage levels of +3, +1, -1, -3 volts."
The above cited Shiva link is very rich, and readable, with information pertaining to not only BRI, but to the primary rate interface (PRI) as well, and a whole swath of other related ISDN data.
Enjoy, Frank C. |
