I support an Asterisk server located behind NAT running Asterisk 11, soon to be replaced with another box running Asterisk 16. At home I run a similar Asterisk server, and connect the two using IAX2. All is working well. Several years ago I set up a remote office with an ATA and it has been running fine since. It is also behind NAT.
Now I need to set up another remote office with a SIP phone, and I am trying to configure it and test it from home. I am confused about port forwarding. I know I can specify different ports for IAX and SIP signaling in iax.conf and sip.conf, and forward those ports at home to the SIP phone and the Asterisk server, but how do I specify separate ranges of RTP ports for forwarding at home? Or, does the endpoint tell Asterisk which range of ports to use for RTP?