Call forwarding no audio either direction

[jonesng]

I have an issue with call forwarding, if anyone else has had similar issues, suggestions for a fix, or any ideas I would be grateful.

Our MBG is in DMZ mode, our PBX is a 3300 on the internal LAN.

Calls are OK incoming and outgoing
However call forwarding fails
E.G. If I forward my DDI to my mobile, then ring my DDI from an external number, the call is transferred to my mobile.  However when I answer there is no audio either side.

I understand this type of issue with no audio could be the result of NAT.  We have a Palo Alto firewall.  All firewall rules have been created as per BT guidelines for their SIP trunks with SIP ALG disabled.

Any assistance appreciated.

Thanks

[NEPhoneGuy]

I'd check your media IPs - sounds like signaling here is happy but what ports and IPs is the RTP streaming from.