[asterisk-users] Cisco 7940 no outgoing audio

[Simon Alman]

Hi All

We have a private network setup (no nat) with three types of phones
connecting to asterisk via SIP. We have Polycom, Grandstream and Cisco
7940 IP phones.

When we ring polycom to grandstream or grandstream to polycom then both
phones can send and receive voice fine and all is well.

When we dial any combination of Cisco and either Polycom, or Granstream
the Cisco, no voice is being sent but the Cisco can receive voice from
the remote phone fine.

When we dial Cisco to Cisco it all works fine.

I am at a loss to figure this out and any help pointing me in the right
direction would be appreciated. We are running an old Asterisk server
with version 1.0.10 (yeah we know) and the same mix of hardware and
configs works fine.

On the new (problem) setup we are running Asterisk 1.4.2 and our Cisco
firmware is 08-2-00.

Any help appreciated.

Regards

Simon Alman