FortiVoice behind Fortigate - with ALG

Not many posts here, but before they move it, I had 1 quick question:

Has anyone been able to use the Fortigate SIP ALG to pass connections for Phones on the internet?

I've setup a test lab with a firewall on 7.0.2  - In my testing ALG seem to be working with SIP Trunks (tested with Sherweb, and VOIP.MS).  

Trunks work with both in and out calling, and rules are proper firing to block unwanted connections.

But Phone sets are the internet are a different issue - they register, and can call - but no audio (either way).

Weird thing is, my 1 test phone that is behind a Fortinet firewall is fully working.

I suspect it is something to do with they way basic routers do NAT for SIP.  The ALG does not pickup and open the audio ports.

I have a ticket with fortigate for them to look at the ALG, but thought I'd check if anyone found the answer here.