No Return RTP stream on PCAP from T43U

[rely1]

Hello,

I ran a PCAP on a T43U provisioned with STUN on unique RTP ports.

I see a one way PCAP of RTP streams from phone to server, but none from server to phone in the PCAP.

I checked that the server on GCP has the firewall rules for UDP 5060-5061 and these ports:
tcp:22, 443, 5001, 5015, 5060, 5061, 5065, 5090
udp:5060, 5065, 5090, 9000-10999

Other phones provisioned with STUN in other remote networks are working fine.
Mobile app and Windows APP are working on this same network where the phone is not working.

Any ideas on what I can check on the phones provisioning settings?

Also, I have set PBX delivers audio.

Please advise.

 

[JohnS_3CX]

Hi,

You should repeat it, but this time also run the 3CX pcap to see if the server send out RTP (and to what IP address).

- If it's sent out but never arrives, your remote firewall is probably blocking them before they reach the phone

- If it's sent out but to the wrong IP address, you need to see what IP the phone declared in its SDP (should be the public IP behind which it connects).

SIP-ALG on the ISP modem or on your firewall is probably getting in the way.

Alternatively, see whether you can get a 3CX SBC to bypass all of these restrictions:
https://www.3cx.com/docs/3cx-tunnel-session-border-controller/

 

[rely1]

I will run these PCAPs on 1/20/2023 and check out results...thanks

 

[rely1]

I ran a lengthy PCAP from the phone. I ran the Telephony Sip Stats from Wireshark and there are NO SIP packets coming from the phone. During the capture I turned off the registration of the extension and turned it back on to kick start the SIP registration process and capture anything from the phone. Neither the phone capture nor the Server get SIP registration from this phone. Strange ! Is this a STUN issue or a SIP issue? I see lots of TLS 1.2 packets and STUN packets being delivered back and forth from server to phone and vice versa.

Does every STUN device need a unique SIP port and RTP port?
I made sure this phone has both a unique SIP port @ 5065 and unique RTP ports from 14020 through 14029.

Any ideas what to check next?

Thanks!