asterisk users - Mar 2005 - * intergation with Panasonic D500 and strange echo

Hi, all !

I have a situation like this:

[SIP Terminals] <-> [*] < -ISDN-PRI-> [Panasonic D500] <->
Telecom (conn to
Telecom is with second PRI card in Panasonic and 16 POTS lines).

Panasonic has 2 ISDN PRI cards (one to Telco, and second to Asterisk), 16 
POTS lines to telco and 32 (advanced hybrid telephone type) extensions.

Idea is to have possibility to have some users on SIP terminals (Cisco 7912 
SIP for now), and to have some users on panasonic extensions.

Everything is working OK (SIP to/from extension (SIP or Panasonic's), SIP to
outside line (it goes out on Panasonics PRI to telco)), except certain type 
of incoming calls from telco.

When a call arrives through the PRI connected to telco and panasonic routes 
the call using DID to SIP ext. through the Asterisk, everything works fine 
(i.e no echo), but if a call arrives to Panasonic either throuhg PRI or 
through POTS lines and gets picked up by attendant and then transfered to my 
SIP phone, I (called party) have an very loud echo of my voice. Calling 
party has no problems with echo.

If I plug asterisk's PRI into telco - no problems at all, but this situation
doesn't suite my needs.

Tried with all possible combinations of echocancel, echocancelwhenbridged, 
echotraining, different compile options in zconfig.h (MMX enabled/disabled, 
diffrent echo cancellers, aggressive suppresor on/off and etc. , noapic and 
nolapic in kernel parameters, but with no success at all.

Little about configuration: Intel 865 chipset board, P4 Celleron 2.8 Ghz 
processor, and 1Gbyte of RAM, TE110P in PCI slot with its own IRQ. Linux is 
Debian with debian 2.6.8 - 2.6.10 kernels tested (no SMP, multithreading 
support since I cannot unload wct11xp module if SMP is enabled in kernel - 
freezes machine). Asterisks tested are 1.0.3 - 1.0.6 STABLE and couple of 
HEADs from CVSs all with same symptoms.

ISDN-PRI (both * to Panasonic and Panasonc to telco) are EuroISDN, hdb3, ccs 
and there are NO alarms/errors on Telco, Panasonic or *.

Anyone with similar configuration and problems, or ideas how to solve this ?

Thank you very much.

Regards,
            Nenad