Tranfer calls on SIP trunks

[Bonker1974]

Hi All,
I have a strange issue on a IP Office 9.1 When I receive a call on a SIP trunk and I transfer that call we lose audio. As long as you dont have to transfer the call it works fine.

Any help would greatly appreciated

 

[Pepp77]

What SIP provider?
Username Authentication or IP authentication?
Are you using STUN?
Do you have SIP ALG/SIP Transformations turned on or off on the firewall?
What firewall?

For reference

On a sonicwall I have found that using STUN and SIP transformations turned off allows speech on twinned/transferred calls. Using STUN and SIP transformations turned on causes all sorts of weird issues. Using no STUN and SIP transformations turned on gives speech. No STUN and no SIP transformations no speech. This is with voiceflex and gamma SIP trunks.

| ACSS SME |

 

[IPGuru]

Lan voip tab

press F1 for help

(hint - keepalives)


Do things on the cheap & it will cost you dear

 

[kyle555]

Does it happen transferring to other extns on your system and/or the outside world?
Does trying 2 IP phones with direct media off have the same issue?

From a SIP signaling perspective, its possible you could be confusing the provider. To say, PSTN calls A (with direct media), A presses transfer. PSTN gets a reinvite to a VCM to be put on hold, A calls B with direct media, A completes xfer to B with another reinvite to the PSTN to phone B.

If you turn off direct media on your SIP line, you'll at least make the media setup with your trunk as simple and static as possible when testing out different scenarios. That way, if/when it boils down to packet captures, at least it'll be a little easier to read!

 

[Bonker1974]

This issue happens on transferring to any exten. Even when you hit the th AA and dial an extension you get no Audio.

 

[Albus2]

Bonker1974,
read IPGuru's tip about 'keep-alives'
...100% the right answer...