[asterisk-users] How to set externip in sip.conf automatically?

[RR]

Mate, I'm beginning to think that it can't be done. As in, maybe
you're not allowed to put anything into externip other a valid IP
address and the $ENV{} variable doesn't really work there. You might
want to decipher your externip by registering your server with a
dynamic dns service and then lookup your IP through an nslookup
periodically. Then do some sort of a check and if the address has
dynamically changed, then rewrite your sip.conf file and do a CLI 'sip
reload' or 'restart when convenient'. Not sure why your IP address
should change that frequently anyway, so the approach I mentioned
should cover you. Maybe there are better suggestions out there.

BTW, In the newer versions, maybe it's in 1.4 only, you can use the
keyword 'externhost' where you specify the FQDN of the server, and it
will then lookup your external ip all on its own. You can then use
externrefresh to tell (*) to look it up every so often. Not sure what
the status of this feature is in current 1.2.x releases

Good luck