I have a customer who is using a couple of different ITSPs to make calls
to the Republic of Ireland (+353). The calls are originated on an Asterisk
box and handed to the ITSP using SIP over a LAN. As far as we know, each
ITSP then routes the calls over the PSTN to Ireland.

At times with both ITSPs, the customer compains of echo on the line. This
only happens with Ireland; calls to other national and international
destinations do not suffer in the same way.

Have any other readers of these groups experienced echo or other anomalies
with calls to Ireland?

Just trying to get ideas at the moment.

Thanks,
Tony
--
Tony Mountifield
Work: - http://www.softins.co.uk
Play: - http://tony.mountifield.org

Tony Mountifield wrote:
I have a customer who is using a couple of different ITSPs to make calls
to the Republic of Ireland (+353). The calls are originated on an Asterisk
box and handed to the ITSP using SIP over a LAN. As far as we know, each
ITSP then routes the calls over the PSTN to Ireland.

The cause of the echo will be poor echo cancellation at the point where
the circuit switched (PSTN) to VoIP conversion is done, as that is the
only sensible place to echo cancel in those circumstances. I'd suspect
there is common infrastructure on the two service providers' Irish
interconnects to the PSTN.

I suppose one other possibility is that the Irish PTT is operating some
sort of VoIP with low enough latency for the echo not to be noticed for
within network calls, but which is too long for the echo cancellers at
the SIP boundary.