No audio on an external call forward across Level 3 SIP trunks

[ssherman@ecsinc.su.com]

i am turning up SIP trunks with Level 3 and have everything working except there is no audio only on incoming calls forwarded to an external number. Has anyone else encountered this issue?

[wiseguy]

I've seen this at a customer. The SIP provider had to change something on there SBC to make it work. In that case the SIP trunks were connected without an MBG and the streaming should be done at there SBC.

[ssherman@ecsinc.su.com]

This is with an MBG in the DMZ. We had firewall issues to begin with , but have straightened that out. The provider is stating it is not their issue. Transferring externally is fine. The issue is only on forwards.

[ssherman@ecsinc.su.com]

Turns out this was a firewall issue.

[sunspark]

Turns out this was a firewall issue.

hello , i have the same issue , do you remember what was the issue ? thanks.