Is it possible to transfer SIP protocol from a local network to another local network or the Internet?

Question

Telephony

Good day, dear audience of the toaster portal. At the moment there is one very interesting and unsolvable problem for me at the moment. There is an office with a SIP telephony server on the local network, a server on ASTESRISK, although this is most likely not important, since I do not administer it. Authorization of client phones from the same office local network passes to this server. The task is to log in to a server from another network, preferably via the Internet. Is it possible to do this with the help of intermediate equipment, such as a router. I connected the Internet cable to the router, the LAN cable to the lan port on the router, there is a static IP on the Internet connection, I tried to forward the resources of the router from the local network to the Internet, but there is little understanding in this matter.

I ask for help in resolving the issue, or at least a push to the right direction of thought.

Answer 1

well, in general, yes, you need to forward a certain number of ports on the router for the server, or rather, for the asterisk on it. these should be the port that is used on the asterisk to receive SIP traffic (usually UDP 5060), and the ports for receiving RTP traffic (perhaps this range is UDP 10000-20000, but it’s more correct to look in the asterisk config, as it is configured after the fact). when forwarding ports, these ports and the IP address of the internal network host to which they are forwarded (servers with an asterisk) are actually indicated.
how to forward ports - depends on the model of the router.
also on a server with an asterisk for each sip account in sip.conf that needs to be able to connect from the internet, you will most likely have to add the line nat=force_rport,comedia.
there may be other nuances: a firewall, binding an asterisk to interfaces. but it's not interesting to guess, I'm more used to answering after the fact.
this is all if we are talking about the Internet and port forwarding through NAT.

Answer 2

If you do not need to connect from outside, then you can do it between vpn routers.
Or site to site or server(remote)-client(your) and connect to telephony using internal addresses

Answer 3

Everyone is rightly advising you, raise a vpn connection and connect directly to the SIP server with a softphone\SIP phone. In this case, you enter the LAN, and the firewall does not bother you anymore.