I am using a local asterisk server on a machine behind a router. The asterisk-server has a fixed local IP and the routers external IP is registered with dyndns and can be resolved from outside my network.
1) I am able to register a SIP client with the server from outside my LAN using the domain name mydomain@dyndns.com
2) I am able to register a SIP client with the server from inside my LAN using the local fixed IP address of the asterisk server
3) Howver, I can't register from inside my LAN using the domain name. As a consequence, I need to change registration settings on my mobile SIP client every time I leave my house (or come back home).
I have tried multiple variations and permutations of parameters in sip.conf (localnet, externhost, nat, domain) but fail to get it right (or find a simple explanation what to do in such a basic scenario). Could anybody please help me with the parameters for my sip.conf? Many thanks in advance...
This issue related to your router. When you use external domain from inside lan, path of packet is different and router's firewall(or sip-alg algorithm) can work different.
You choices are
Change router. Simplest way.
If router have linux/openwrt inside - fix firewall
If router have linux/openwrt inside - change dns server to give local ip for requests from inside network.
if router support SIP-ALG - try turn that off.
Use softphone with more then 1 sip record(for example zoiper free version).