[Asterisk-Users] Help in E1-T1 encoding

[Alejandro G]

The call is received from the PSTN by an NMS E1 with ISDN Pri (EuroISDN) and
is switched to the NMS T1 using NMS MVIP internal bus switch that is similar
to a H.100 bus with few streams/timeslots.

Once in the T1 (which is running National ISDN 2 Pri) this board "calls" the
TE110P in asterisk which is connected by a loopback cable. Asterisk receives
call, asnwer it and do the stuff planned in the dialplan. Both T1 boards
where first configured using ulaw and then alaw. In both cases the sound had
distortion.

Today I test another configuration trying to isolate error. Instead of using
a NMS T1, I used another NMS E1 and I configure TE110P as an E1 using in
both boards also EuroISDN and everything began to work fine. I also connect
the TE110P to a live E1 and again everything is Ok. I not sure that the
distortion is an encoding difference but it really seems that there is the
problem.

Configuration for T1 in zaptel.conf

span=1,0,0,esf,b8zs
bchan=1-23
dchan=24
alaw=1-23

I check with command in CLI zap show channel 1 the Default law indicates
alaw as expected. If I comment last line works the same but it indicates
ulaw.

zapata.conf:

callprogress=no
signalling=pri_cpe
switchtype=national
overlapdial=yes
usecallerid=yes
hidecallerid=no
immediate=no
echocancel=no
echocancelwhenbridged=no
callerid=asreceived
context=incoming-call
channel=1-23
language=es
rxgain=0.0
txgain=0.0

Sorry for so long mail and thanks.


Alejandro Ghergherian