[Asterisk-Users] E100P and T1 channel banks

[Chris A. Icide]

On 05:52 AM 7/12/2004, Anton Tinchev wrote:
 >Andrew Kohlsmith wrote:
 >> On Monday 12 July 2004 07:36, luan au wrote:
 >>
 >>>Could you kind Asterians (should we pick Asteroids then?) confirm if I
 >>>can use an E100P card with a T1 channel bank via * please? I live in the
 >>>UK hence the question.
 >>
 >>
 >> Yes.  You''l only get 24 channels but it shoudl work fine.
 >>
 >> And I prefer the term "Astericians" (think electrician), myself.
 >>
 >> -A.
 >Any signaling and framing issues?

I can't imagine that this would work at all.

TDM multiplexes a set of signals over a certain time window, thus being 
able to transmit multiple channels over a single transmission line.  In 
other words, there is a set of windows in which we transmit data.

In a T1 we have a set of 24 channels and a 1.536 MHz (where in the world 
did that clock speed come from?) clock is used to sequence the 
channles.  Each channel is 64 kHz and 24 are stacked together to make a 
signal, so in one cycle you transmit 24 "frames" one frame for each channel 
(1,2,3,4,....24) and then go back and do it again...  the real signal for a 
channel is achieved by taking each frame for that channel (which is every 
24 frames) and putting those together to get a channel.

The problem you have is that E1 uses a 2.048 MHz signal and T1 a 1.536 MHz, 
so right off the bat your timing is going to mismatch, so there is no way a 
T1 port will natively work with an E1 port.

I'm not sure, but I think the 4 port cards will run T1 or E1 mode (never 
had to find out before), but the T100P and E100P are limited to T1 or E1 
(again, this is from memory of reading mail list), so I may be wrong.

However the answer to your question is you can't plug T1 and E1 hardware 
together unless one or the other has an autodetect and autoselect function 
allowing it to switch clocks, framing and coding.

T1's use d4 or esf with ami or b8zs as framing and coding
E1's use something completely different ccs, cas?  sorry, I'm not up to 
speed on E1, but a quick glance at a zaptel.conf sample should let you know.

-Chris