Can somebody help me? I am configuring a connection to a sip account. I can make phone calls. Nobody can call me. The error message I get is No RTP Packets were received on 00000018@remoteraddr=220.127.116.11:18074:extaddr=0.0.0.0;localaddr=10.0.0.12:35012. When somebody calls me the phone rings. And there is no voice. Everything else works fine. My firewall show that the 3CX IP PBX is sending data to 18.104.22.168:18074 It should send RTP packets to 22.214.171.124 Using ports 23000 to 24000. The 3CX IP PBX is sending RTP packets to 126.96.36.199, using ports 23000 to 24000 when I make a phone call. That works fine. The ISP doesn’t support stun.