[Asterisk-Users] Noises and echo effects

[Serge Oleinikov]

Hi!

I need your advice. My problem is that I have very bad sound quality calling to cellular phone via asterisk router.
There are some kind of noises and echo effects when you try to speak louder. 

I have the following components in my call routing schema:
 - PBX with E1 port.
 - asterisk router with TE405P card(32bit/4 E1 ports).
 - Teles server with PRI interface card(3 E1 ports) and VTM interface card (4GSM)

I have 2 call routing schemas:

 (PBX[E1])-->(*[E1])-->(TELES PRI + VTM CARD)=>[cellular]       (1)

 (PBX[E1])-->(TELES PRI + VTM CARD)=>[cellular]         (2)

As you see the difference between (1) and (2) is intermediate asterisk router.
Using (2) I have acceptible(good) sound quality, but using (1) I'v got noises and echoes on the cellular's side.
Asterisk connected with Teles server by the means of the cable. Cable length is less than 50 santimeters.
Cable is not the root of the problem. The have already checked this possibility.
We got a lot of solutions based on asterisk and all the calls have good sound quality. 
The only exception is for (1). What do you think what is the root of my problem?
I also tryed to modify variouse parametrs values in my zapata.conf to solve the problem. Useless.

Here is my zaptel.conf 

span=1,1,0,ccs,hdb3,crc4
span=2,1,0,ccs,hdb3,crc4
span=3,0,0,ccs,hdb3,crc4
span=4,0,0,ccs,hdb3,crc4
# Span 1
bchan=1-15
dchan=16
bchan=17-31
# Span 2
bchan=32-46
dchan=47
bchan=48-62
# Span 3
bchan=63-77
dchan=78
bchan=79-93
# Span 4
bchan=94-108
dchan=109
bchan=110-124

loadzone=us
defaultzone=us


and zapata.conf

[channels]
switchtype=euroisdn
context=empty
signalling=pri_net
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
overlapdial=yes
usecallerid=yes
usecallingpres=yes
hidecallerid=no
transfer=no
threewaycalling=no
callwaiting=no
callwaitingcallerid=no
callreturn=no
rxgain=0.0
txgain=0.0
pridialplan=unknown

-------- CUT -------------

group=4
context=group4
signalling=pri_cpe
immediate=no
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
overlapdial=no
jitterbuffers=0
channel => 94-108
channel => 110-124

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