[asterisk-users] PSTN Calls from SI.P: buzzing and pops

[Allen Casteran]

We have SIP phones connecting to *, and our PSTN lines connecting 
through an Astribank FXO.

Internal Sip<->SIP calls are clear.
External calls through the Astribank get occassional low level buzzing 
for about 1/2 - 1 sec at a time.

Those are usually accompanied by some light pops or static

No transcoding, all ulaw.
PSTN lines come from an Adtran IAD channel bank about 10 ft of cable 
from the Astribak. Astribank and Adtran are both chassis grounded to our 
  UPS.

Tried set echocancel=on and echocancel=off in the zapata.conf... No 
difference.


Any ideas??

Thanks,
Allen.