Kevin,
As we discussed over e-mail, the issue you are seeing with all of your different phone models is related to the way you are testing failover. If you create a null route to the SIP server and the ADTRAN does not have a path to the SIP server, it will respond with a 480 unless the device is a gateway and the call is routed to the internal B2BUA (resulting in a 404). The best way to test failover to cover a single server failure scenario would be to kill the route on the upstream router.
Just to be clear, the feature we are adding in Q3 is support for Polycom Geo-redundancy. What that means is that we will spoof the layer 3 address of the SIP server for all SIP requests sent to the phone (we currently use the L3 address on the egress interface facing the phone). We have only seen this issue with Polycom phones.
Regards,
Rob
ADTRAN Support
