[HELP NEEDED] Calls hanging up on answer

[hsl]

Hello guys,
we recently set-up a 3CX instance on AWS through PBX express.
This is just a test system and we looking forward using as a production system (and buy a license) once everything will be up and running.

Every feature is working as a charm but internal call originated by our only desk phone (a Grandstream GXV3350) are being hanged up on answer.

Here are the results so far:
- Grandstream (configured as extension 00) ---> 3CX App (extension 03) : HANG UP ON ANSWER (failed call)
- 3CX App (extension 03) --> Grandstream : WORKS!
- 3CX App (extension 00) --> 3CX App (extension 02/03) : WORKS!

We were wondering if this could be caused by this model not being yet supported by 3CX. We tried to forcely provision it by selecting a similar model but despite the fact that the config has been successfully applied, the issue remained.
It could be worth saying that our app is currently using a 3CX tunnel on port 5090.

Here are some screenshots of our dashboard:




Logs:



Thanks for your help.
Hope we'll figure this out together.
Simon

 

[FS_Mathieu]

I don't like using 00 and 03 as extension number, it could be specific codes. Prefer 100 / 500 / 1000 or smthg like that.

I'll tell you to try a packet capture when the call is hanged up to have a better view.

 

[Alphabetic]

What happens if you call the echo test from the grandstream? Dial *777

 

[JohnS_3CX]

Try as @kieferschild said, and see if you get the echo test.

If not a supported phone it may work, but you might have to manually find what is stopping it and adjust it accordingly.

A capture from Activity Log and analysis in Wireshark will tell you more (if you are familiar with pcap analysis).

 

[hsl]

What happens if you call the echo test from the grandstream? Dial *777

the echo test is definitely working! Could hear my voice

 

[hsl]

A capture from Activity Log and analysis in Wireshark will tell you more (if you are familiar with pcap analysis).

Thanks for your reply guys.
I opened the generated pcap file in wireshark but all I could see are encrypted TLS packets, handshake messages and ARP queries.

Is there anything specific I could check?

Thanks again!

 

[hsl]

Did another test...
apparently this issue occurs only when the extension I'm dialing answers on the 3CX app!!

- Grandstream GXV3350 --> 3CX Chrome web extension : WORKS!
- Grandstream ---> 3CX App (extension 03) : HANG UP ON ANSWER (failed call)

At this point...I believe that the issue is related to the app, maybe some misconfig

 

[Alphabetic]

Can you confirm when you say "3CX App" which you're referring to and what the version is?

 

[hsl]

Can you confirm when you say "3CX App" which you're referring to and what the version is?

latest stable version from iOS appstore (16.02)

 

[Alphabetic]

Does it hang up on both local and remote network?

What are your provisioning settings for 3CX app under the EXT?

 

[hsl]

Does it hang up on both local and remote network?

What are your provisioning settings for 3CX app under the EXT?

Yeah, it hangs up on both devices. Sometimes it doesn't even ring on the other side.

there it is:

 

[Alphabetic]

Can you change RTP to normal, reprovision and try again?

I would go back to your Wireshark capture and check what's going on, on a network level.

Once you've got the capture you can go to Telephony > VoIP Calls and check the flow.

 

[hsl]

FIXED!!
I just had to disable the 3CX tunnel setting on 3CX's app (or on extension's provisioning settings) and connect directly!





Thanks everybody for your support!!

 

[JohnS_3CX]

Actually it is best to remove the secure RTP and enable the tunnel then reprovision.

This way both the RTP and SIP will be encrypted.

 

[hsl]

I see... but would the tunnel be compatible with my Grandstream phone?
Also, the GXV3350 model isn't still officially supported by the 3CX autoprovisioning.

 

[JohnS_3CX]

Hi,

The tunnel is purely between the PBX and the app.

The Grandstream does not talk to the app, it talks to the PBX that sits between them and relays the audio.

The issue you were facing was due to the misconfiguration of the app. settings under the the extension which is something entirely unrelated to the Grandstream.