Phone problem losing connection with the hosted 3CX server

[Artefact]

Hello,

We have a problem with 5 Yealink phones (T33G/T57W/ DECT) on a same site that are configured to connect with STUN on a hosted 3CX.
Phones can contact the server and retrieve the configuration in auto-provisioning.
The calls work for a while but the phones end up losing the link with the 3CX server. Phones keep the resgistered status but an internal/external call does not arrive on the phone.
All phones have custom SIP and RTP ports, for each phone, and the PBX Delivers Audio option is active.

We also have random behavior with internal calls that don't have sound or don't ring. After rebooting the router, the phones disappear and do not return to 3CX without manual action.
We have try to install an SBC on site but we have the same problem.

On the server side, the configuration is correct and 3 phones integrated from another site does not seem to encounter any problem.
Do you have an idea to correct this behavior ?

 

[ChrisC_3CX]

My recommendation would indeed be to switch to SBC. What do you mean that you tried to install the SBC but you had the same problem? Did you factory reset all phones and then provision them using the SBC provisioning method or did you just install the SBC and leave the IP Phones as is?

Please also provide the info here: https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

 

[Artefact]

Hello Chris,


We installed an SBC on site and reconfigured the phones to use it. We didn't do a factory reset but we reprovisioned and reboot the phones and they went back up through the SBC to the 3CX server. Eventually we must use the STUN for this site.

For the informations

• 3CX Version : Standard Annual 16.0.8.9
• Server OS : Debian 9
• Is the 3CX Server Hosted and where? : Server Hosted by us
• IP Phone Make/Model/Firmware : Yelink T33G (124.85.0.40), T57W (97.84.0.125) and DECT W52P (25.81.0.30)
• Provisioning Method: STUN
• Trunk Provider or Gateway Make/Model : OPENIP
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: YES

We respect all the requirements for the stun of your link and we have remove the box with a SIP alg.

 

[ChrisC_3CX]

As a first note, do bear in mind that IP Phones must always be reset when changing the provisioning method used.

If you can use a 3CX SBC then I recommend you do but make sure that all devices are running the 3CX Supported firmware(T57W must be running 96.86.0.5), have been factory reset and reprovisioned as SBC devices using the default 3CX Template.

If you are dead set on using STUN, then make perfectly sure that all configuration mentioned in the provided guide has been taken care of. I cannot stress this enough and am mentioning it again because the description of your issue suggests that it may be related to STUN IP Phone misconfiguration.

If absolutely sure that the correct configuration applies, factory reset and re-provision using the 3CX default template instead of the custom ones and let me know if the issue persists.

 

[cobaltit]

You mentioned that the phones all have custom (hopefully you mean unique) SIP and RTP ports, but no mention of those ports actually being forwarded through the firewall. That is the other requirement.

 

[Artefact]

Yes the phones have unique ports for sip ( 1 port ) and RTP ( 19 ports ). A NAT is done from the firewall to the phones on their dedicated ports. NATs are filtered in IP to let pass only the IP of the 3CX server.

I made progress by disabling the "Scrub" option in the firewall. Now my extensions can communicate with each other in the office! Except for a phone that receives audio but doesn't send any. The phone have been factory reset but without change. It use port 5070 (SIP) and range 14020 to 14039 (RTP). Any idea where is the problem ?

 

[ChrisC_3CX]

Since you're still getting the same after following the guides you may have to dig deeper to find what the problem is as it may reside on the network level. I would highly recommend getting in touch with a 3CX Partner to help you with troubleshooting this further.