Grandstream GRP2612 - No Audio When Call Is Connected/Answered

[John W]

Hello,

I am wondering if someone can help me out. I am new to adding VOIP desk phones to 3CX, I have a Grandstream GRP2612 that will be used at a remote location. My 3CX server is hosted on an AWS EC2. I was able to get the phone provisioned and assigned to an extension. The issue is that when I make a call the phone rings but I can not hear the other person nor can they hear me. Also if the other side ends the call it shows on the phone as still connected. Also if some calls my main number or the extension that the phone is assigned to it will ring on softphones and the web UI but not on the VOIP desk phone. I have forwarded the SIP and RTP ports on the LAN where the phone will be located.

Some troubleshooting I have done:
1. I have forwarded the SIP and RTP ports on the LAN where the phone will be located.
2. I have run a firewall check on my 3CX server and all comes back green
3. Have checked and enabled: Use PBX for Audio

Any help would be greatly appreciated.

Thanks

 

[JohnS_3CX]

Hi John,

While you have done well in port forwarding and checking the firewall, you may still face issues exactly like the ones you describe. This is usually due to factors that you may not be able to ultimately control (like the ISP doing things to SIP after the traffic leaves your network).

I would recommend to install a 3CX SBC at the site where the phone is to see if you can bypass the restrictions:
https://www.3cx.com/docs/3cx-tunnel-session-border-controller/

Then, factory reset the phone, and delete it from your extension.
You can go to the phones page and use "Assign Ext." to add it as an SBC phone this time around.

When it comes up, try making a few calls to confirm the issue was resolved. If it solves your issue, you can be almost certain that your traffic was either being blocked / modified at a later hop after it leaves your local network.