No audio with Avaya IP Office / One-X Mobile App through 100D

[daccu]

Hopefully a Fortigate expert out there has had experience with One-X, because this problem is killing me.  We have been trying for months to get our One-X mobile application (part of Avaya IP Office) to pass audio when connected to the Internet.  The app works fine when on the internal LAN, so it doesn't seem to be an Avaya problem.  However when trying to connect over the Internet it connects, shows a all green on the status indicators, I can listen to voicemails on it, and when I place a call it will ring but when the other party picks up there is no incoming or outgoing audio.

Things I have done:

Ensured both internal and external DNS entries match

Gave both IPOffice and One-X their own IP addresses and during testing allowed traffic on ALL ports

Made sure that the app had microphone access on the iPhone (a silly issue that I found during the first round of troubleshooting)

I'm at a loss.  It's like it has full connectivity to the One-X server (which is shared with VMPro), but not the IPOffice server.  I can connect to the html server of IPOffice remotely so I know the IPs are mapped right.