[Asterisk-Users] Incoming DID call Voice Problems

[Bisker, Scott (7805)]

Hello All,

I am experiencing some intermittent problems with calls coming inbound on my DID trunk.  I have 12 DIDs that come into an Adtran 750. From there T-1 to a port on T400P.  The problem is that some calls that come in don't seem to bridge properly.

Heres what happens.

Call comes in on Trunk.
Call Routed to correct Zap Channel.
Phone Rings.
Person Answers phone, but hears nothing but their own echo.
Calling party hears everything fine.

I have MARK2 enabled in Zaptel driver for echo problems on my PRI line.


I can't seem to replicate the problem calling out PRI to the DIDs, or from a cell phone.


I can reliably replicate the problem with an offsite customer that calls in.


Any idea what may be causing this?

Thanks in advance.