[Asterisk-Users] Delayed echo

[Bart Roos]

Hi There,

I have a really weird problem, I hope you guys can help me out on this one.

I'am running an Asterisk box with one HCF_PCI ISDN card that connects to my
telco. I'am experiencing a strange delayed echo during conversations between
our sip phones and outside callers that are using older PSTN equipment.
During these conversations I can hear myself with a 0.5 to 1 second delay.
This feedback has the same volume as the voice of the caller on the other
side. The caller on the other side doesn't experience any echo whatsoever,
but it's really disturbing on our side and makes this calls almost
impossible.

I don't have any echo problems with calls between SIP phones, calls to GSM
phones and calls to remote ISDN phones. It only occurs when calling to old
analog equipment.

I've been reading all the FAQ's and documentation, but I couldn't find
anything about this particular problem. Does anyone have any suggestions?

Thanks,
Bart Roos
The Netherlands