- 1. I am very perplexed. I have closed all ports on my router (no forwarding) (Ubiquiti edgemax)
2. Sip registers fine with 3CX to VOIP provider (voip.ms)
3. first call on either of my SIP trunks goes to busy signal
4. As soon as I run the port checker, and services are restarted, all calls start to succeed.
Is it ok to leave the ports closed?
what is magic about the port checker?
Is this success related to the STUN server pinging #CX behind the NAT (and it succeeds because the 3CX originates the request?)
Just trying to learn...3CX forum says this may or may not work long term....