AS5350XM running 12.4.15(T)7 with UBE (ip-ip gateway) code.
This box is acting as a gateway supporting PRI trunks, a hosted VOIP provider, and some users with SIP IADs.
The hosted VoIP provider uses a hostname as the SIP peer for load-balancing and redundancy. When it receives an INVITE, it returns a 302 redirecting the call to a contact of the IP address of the actual gateway for that call.
Calls from the PRI trunks to the 5350 properly handle the 302 and send a second INVITE to the IP, the call completes normally.
Calls originating from a SIP IAD (sip-to-sip) go through the same initial scenario, but the 5350 fails to honor the 302 and sends another INVITE to the hostname, resulting in another 302, looping and not completing.
I can't find anything in bug tool, have tried several options under the voice service voip config section with no luck.