I'm trying to set up 3CX fax to email from a VOIP provider. I've tried 2 different providers -- both with the same problem. If I call the DID with my cell phone I can here the fax tones. If I try to receive a fax, it answers and then after a while hangs up and 3CX logs "No RTP packets were received". I don't know what to try to do to troubleshoot/fix this. Any direction would be appreciated. L.