Using Proxy To Log Into Sip?


I use Bria Mobile to connect to my PBX and have a question. Is there such a thing as a SIP proxy that I can use? Bria supports an “Out Proxy”. I’m asking because recently I locked down my FreePBX firewall to only allow from our hardwired internet IP’s and that means if someone is on a cellular IP they will be denied access, but if I can proxy it and get the IP address/range of the proxy server then I can allow that instead. If there is a way to do it, do you have recommendations?