[Asterisk-Users] No sound on 10% of incoming calls

[Jerome SOUCANY]

Hello,
 
I have a problem with Asterisk, on 10% of incoming calls the IP Phone ring
but I don't hear the caller and the caller doesn't hear me (all IP Phones
have the same problem).

This problem appear also if the call is directly send to the second E1 of
the digium card who is connected to an IVR.

It does not depand on the charge of the server (I have the problem with only
one call).

The configuration :
 
PRI (France Telecom) 15 channels  <====> Asterisk <=====> IP Phone
 
* Server : 
        - Dell power edge 1800SC
        - 2 Ethernet cards (LAN + VoIP LAN)
        - Digium card : TE 405P
        - Linux Mandriva LE 2005 (10.2) :
          Linux ASTERISK 2.6.11-12mdksmp #1 SMP i686 Intel(R) Xeon(TM) CPU
3.00GHz unknown GNU/Linux
	  - Asterisk 1.2.4
        - Zaptel 1.2.3
        - Libpri 1.2.2

* IP Phone :
	SNOM 320 (latest firmware)

============================================
zaptel.conf

span=1,1,0,ccs,hdb3
span=2,1,0,ccs,hdb3,crc4,yellow
span=3,1,0,ccs,hdb3,crc4,yellow
span=4,1,0,ccs,hdb3,crc4,yellow

bchan = 1-15, 17-31
dchan = 16
bchan = 32-46,48-62
dchan = 47
bchan = 63-77,79-93
dchan = 78
bchan = 94-108,110-124
dchan = 109

loadzone = fr
defaultzone = fr

============================================

============================================
zapata.conf

[channels]
switchtype=euroisdn
pridialplan=national
signalling=pri_cpe
usecallerid=yes
hidecallerid=yes
usecallingpres=no
callwaiting=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
cancallforward=yes
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
rxgain=0.0
txgain=-6.0

group=1
callgroup=1
pickupgroup=1

immediate=no
callprogress=yes

callerid=asreceived
group=1
context=from-pstn
signalling=pri_cpe
channel => 1-15    ;,17-31  => only 15 first channels on PRI

group=2
context=from-ivr
signalling=pri_net
channel => 32-46,48-62

group=3
context=from-ivr-bis
signalling=pri_net
channel => 63-77,79-93

group=4
signalling=pri_net
channel => 94-108,110-124
============================================




Any ideas ? 



Regards

Jerome