Remote phone with multiple call servers

[h382]

Client has redundant internet connections at main office. He would like his remote phones to be able to "re-register" to the backup IP address in the event the primary fails.

I currently have the phone working as a remote NAT phone to the primary IP Address. I do not know if the the IP Office works similar to the CM where you can add multiple registration IPs into the 46xx settings file. My concern is that it won't work because I have the System -> LAN1 -> Topology -> Public IP Address set to the Primary IP, and in the case of a failover, this won't match.

When I attempt to register the phone to the backup IP address currently, it automatically registers to the primary.

VPN route may work, if it's possible to have multiple VPN registration IP addresses, which again, I'm not sure of.

The firewall is managed by 3rd party vendor, so specific questions I might not be able to answer quickly.

Has anyone tried to do this?

Edit: Version 9.0.12

 

[IPGuru]

Using Nat traversal - NO

Nat traversal is also a VERY BAD idea as it does not work reliably & exposes the IPO to a greater risk of hacking​

VPN, Not 100% sure on this one, I suspect not check Avaya's configuration document to be sure

https://downloads.avaya.com/css/P8/documents/100092405

Do things on the cheap & it will cost you dear

 

[h382]

After giving it some more thought. I think the only way to accomplish this is using the VPN with a DNS name for the VPN registration. I found a 3rd party service that will act as a "primary and failover" DNS pointer. Typical DNS services that associate a DNS name to multiple IPs use them in a round robin fashion for load balancing, and that's not what I am looking for.

Open to other suggestions if people have tried this before.