We have two broadband connections both connected to our Draytek 2850 and we have a Sip trunk authenticated by one of our broadband IP address connected to our PBX. The Sip trunk is provided by Gamma telecoms and only one IP at a time can be set for authentication (or so I've been told).
My question is, when WAN 1 fails the Draytek will auto fail over to WAN 2, our internet continues to work, however our Sip trunk is not authenticated on WAN 2's IP address and does not seem to work.
How can this be set up, or if not then what is a reasonable alternative?
Any questions please ask.