[Asterisk-Users] Echo Cancellation, TDMoE fails, X100P works

[Gary Mart]

>> System Diagram:
>>                             +- PRI --> modem bank
>>                             |
>> LEC <-- PRI -->  * with  <--+
>>                  T400P   <--+
>>                             |  (pri)
>>                             +- TDMoE -->  *
>>                                           with  <-- SIP -->  sip phones
>> LEC <------ analog line --------------->  X100P
>
>
>> PS  The modem connections have been working just fine after some initial
>>     problems and a CVS update.  Thanks Mark!  
>
>
>Would you be willing to share your T400P/NAS configuration?  I intend on 
>doing something very similar but was told that the T400P couldn't pass 
>traffic between the LEC PRI and the NAS and achieve v.90/v.92 connections.

Oh, but it DEFINATELY can!

# file: /etc/zaptel.conf  (on * with T400P)

loadzone=us
#                             pri from LEC
span=1,1,0,esf,b8zs
#                             pri T1 to portmaster (this one is online)
span=2,0,0,esf,b8zs
#                             pri T1 to portmaster (backup, testing)
span=3,0,0,esf,b8zs
#                             pri T1 (unused, next I will try using this to
#                             connect to the other * box if I can't stop the
#                             echos on TDMoE)
span=4,0,0,esf,b8zs

bchan=1-23
dchan=24
bchan=25-47
dchan=48

# For Testing: This maps channels straight across with as little involvement
#              as possible by * (the zaptel driver just shuffles bits).
# dacs=1-24:25

bchan=49-71
dchan=72
bchan=73-95
dchan=96

# TDMoE channels to PBX (* with X100P's)
dynamic=eth,eth1/00:01:02:9B:39:72,24,1
bchan=97-119
dchan=120



# file: /etc/asterisk/zapata.conf
[channels]
language=en

context=lec-pri
signalling=pri_cpe
switchtype=5ess
usecallerid=yes
group=1
echocancel = no
echocancelwhenbridged = no
channel => 1-23

context=outbound-pm
signalling=pri_net
switchtype=5ess
usecallerid=yes
group=2
echocancel = no
echocancelwhenbridged = no
channel => 25-47

context=outbound-pm
signalling=pri_net
usecallerid=yes
group=3
channel => 49-71

context=local
switchtype=5ess
signalling=pri_net
usecallerid=yes
group=4
channel => 73-95

;; TDMoE to PBX
context=local
usecallerid=yes
signalling=pri_net
group=5
channel => 97-119



# file: /etc/asterisk/extensions.conf

(excerpt)

[lec-pri]

; these numbers to our portmasters

exten => 5413452121,1,Dial(Zap/g2/5413452121)
exten => 5413452122,1,Dial(Zap/g2/5413452122)

; these DID's to PBX via TDMoE

exten => 5413452123,1,Dial(Zap/g5/5413452123)



Note the commented out line in zaptel.conf (# dacs=1-24:25). This was
new in CVS as of a couple of weeks ago and this was the first thing
that worked successfully with the 56k modem traffic.  Also note that
echo canceling is off in zapata.conf, it could only confuse the
modems.  Also, either * is _very_ fast when it shuffles bits between
channels and/or modems have some decent echo canceling software
builtin, because the modems operate at full speed.

Also note that neither the 'c' option nor the 'd' option is used in the
Dial command in extensions.conf.  In all of our tests before talking to 
Mark we had used those options (seemed the obvious thing to do judging
from their descriptions).  Mark suggested taking them out, we did, it 
worked.  (I don't know if that is the whole difference between what worked
and what did not.  This was one of those situations where you go in thinking
the solution is straight forward, but after 6 or a dozen failed attempts 
you realize that you are in for a big trial and error session and you have
not kept exacting records on the initial failed attempts.)

Let me know if that helps.

Now, it seems to me that the only reason you would want to do what I did
is so that you can route some of the incoming calls somewhere else for 
another purpose, like a voice call.  And somewhere along the line you
will run into my problem: echo cancellation.  Maybe you can help me out
there.

>
>Also, your diagram looks like you're connecting two * boxes by plugging one 
>end of a cable into an ethernet jack, and the other into a T400P jack -- is 
>this correct?  I thought TDMoE was strictly ethernet<-->ethernet?

I left out some details for the sake of brevity.  Both * boxes have 2 ethernet
interfaces, one for normal IP and the other dedicated to the TDMoE traffic.

>
>
>Regards,
>Andrew

Gary