[asterisk-users] SIP to IAX2 with delayed echo

[c james]

A Polycom 550 and a IAX client (Mozphone and ZoIPer were used) are
having a conversation.  Call quality is reported as good except for an
echo with a 3 second delay.

Most of my searches are saying echo happens only on the PSTN piece, but
there isn't one here.

Can someone point me in the right direction?

Asterisk 1.4.21.2
Under 40 users
Quad-Core AMD Opteron(tm) Processor 2352 and 4G RAM (Hey, that's what
they wanted to use!)