Echo IP to PSTN via PRI

[norlee]

Hi,

We have a CS1000S release 4.5 with ip sets (i2002 p2) and analogue phones. The only trunks on the CS1000 is a single PRI (DPNSS) to an network of older PBX's which have the PSTN connectivity, the PRI is transmitted via a microwave link.

IP to IP is fine. IP to other PBX's is fine as well. Analogue to IP is good, analogue to other PBX is good and analogue to PSTN is good.

The problem is IP to PSTN (breaks out of the older PBX network) Callers on the CS1000 get their own voice echoed back to them. The other end of the call is fine.

All deplists on call server, sig server and media cards up to date. Additional peps for a known 'echo at start of call' problem also applied even though not our scenario exactly.

VGMC have latest firmware and phone firmware is pretty recent. Have tried an 1120 with no improvement either.

Echo cancellation is switched on in element manager.

Running out of ideas apart from external echo cancellation, but that would be an expensive route to go down if it does not help any.

Any assistance would be appreciated.

 

[norlee]

Sorted.

The distant switch was ignoring it's least cost routing table (I was sending my PSTN number prefixed with a 9) and sending my call out via a default route, that being an analogue trunk.

Inserting a code to force the DX to route via DASS resulted in no echo.