For Voip purpose, I'm looking to ways to create a peer to peer connection.
I already use a STUN-like server in order to connect 2 peers together. It works great for most NAT, but as expected, this technique does not work with symmetric NAT and random port affectation.
Most of Cellular network uses unfortunately symmetric NAT (even if they allow VOIP).
So I was wondering, would it work if each client sends an UDP packet to my rendez-vous server, in order to exchange each information (ip - port) with each others. Then does a "ip-spoofing" technique from each client, making think the other Peer's NAT that the data is coming from my own rendez-vous server's ip. (Since the port as been opened on each Nat with the outgoing data)
It would let me avoid to create a proxy server that only use bandwidth for realying data from one peer to another.