I don’t see how IP based authentication on a SBC/PBX has any issue at all really?
How often are you changing your SBC/PBX IP address? I would think hardly ever? Also, throw a load balancer in the mix as the authenticating IP and any change of IP address is resolved. However none of this affects where you are pushing calls from, as that is a question for the connection between your handsets and PBX/SBC. It should be invisible to the trunk as a geographical matter.
The issue of authenticating handsets in this way is kind of moot as I am never ever going to authenticate a trunk directly to a handset.
That’s my question really, why is failover not being handled internally using internal networking like SDWAN. The only real point of failure should be the load optimisers or firewall, everything else should be invisible to the trunk.
I can understand failure at the load optimisers or firewall level being a problem, but there’s always a single point of failure somewhere.