One limitation of Asterisk has always been that if it’s behind NAT, it can know only of one external IP address, which it puts in the SIP messages that leave your internal network (with calls to your voice service provider e.g.).
Now a lot of people are using more than one ISP and have e.g. two internet connections for fail over.
In that case the solution with Asterisk is to instead of a specific external IP address, to use an external hostname, which gets updated after a fail over event.
This is however an inferior solution, as the hostname might not get updated immediately and then you won’t be able to make outbound calls for a while.
Has the Asterisk team ever considered to do something about this problem?
It would be great if you could specify several external IP addresses.
So e.g. when sending a SIP packet to public IP address A (sip provider abc), then put external IP address 1 in the sip header. When sending to public IP address B, then use external IP address 2.
Or let the user set an external IP address in the endpoint configuration in sip.conf (or pjsip.conf), overriding the general settings on a case by case scenario. (So a different external IP for each trunk).
The user would also configure static routes on the linux server to route the traffic accordingly if needed.