[Asterisk-Users] SIP->IAX->SIP silences

[Linus Surguy]

Hi all,

We've got a number of users connected in a configuration which is basically:

(a)

SIP Phones -> Asterisk -> IAX -> Our Asterisk -> Cisco AS 5xxx (SIP) -> PSTN

We also have users in a configuration:

(b)

SIP Phones -> Asterisk -> IAX -> Our Asterisk -> Digium E1 -> PSTN

The second server in both cases is the same.

The SIP phones place a call via these configurations to the PSTN

Users in configuration (b) are happy. Some users in configuration (a) 
complain that <x> seconds into the call, the called party suddenly hears 
silence for <y> seconds, and then call corrects itself.

Finally, we also have users in configuration (c):

SIP Phones -> Proxy -> SER -> Cisco AS 5xxxx -> PSTN

These users are also perfectly happy.

I suspect, given the history of SIP/IAX/SIP timestamps, something is being 
'changed' which upsets the Cisco gateway resulting in the silences being 
sent.

Any ideas or suggestions?

Linus