So I used word to do a "Compare Document" and accepted most of your changes...For example, I'm setting this up on Line 8, so I used your line 1 settings for line 8 and kept my line 1-4 as they were. Any config changes, I applied yours with the thinking I can use my Operational settings to revert back if something went sideways.
I still have the same issue - Connects to the Obi, places the call on SP1, the other side rings (and I hear ringing), but when the other side answers it disconnects. I'm pretty sure it's not a NAT or ALG issue, as the TGP and the Obi are on the same subnet, and the Obi can place calls through a POTS handset. My FreePBX can also place calls via a SIP account and through the Obi (via SP4).
I set the Obi to "Log Level 7", Sp1 (GV) and Sp3(TGP600) to "Log All Messages", and the TGP to the SIP Debug level 6. I've attached the log for the disconnected call. Unfortunately, I cannot see what is causing the disconnect, although I see where the TGP and the Obi both disconnect.
I've attached my operational values as well as the failed call logs.
I welcome any and all thoughts...