Issue Transferring Calls

[AlexWebster]

We have an issue transferring calls from a Yealink T27G phone to others.
The receiving phone ends up on hold and the call never comes through.

This does not happen with the other handsets (w52h)

Running 16.0.8.9, going to upgrade this evening to see if it makes any difference.

Have tried:

PBX delivers audio
Enable multi calls

Any suggestions? Let me know if you need more info.

 

[JohnS_3CX]

Hi Alex,

Have you tried factory resetting the phone and then reprovisioning it?

But before we proceed, please read the below and provide use with some more information about your deployment:
https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

 

[AlexWebster]

Hi, thanks for you response.

• 3CX Version,
  

  18.0.237

• Server OS, Debian
• Is the 3CX Server Hosted and where? Amazon AWS Lightsail
• IP Phone Make/Model/Firmware version, Yealink T27G / W52h
• Provisioning Method: STUN
• Trunk Provider or VoIP Gateway Make/Model, Dial9
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

I have some more info to add.
Disabling PBX delivers audio - call transfers work between the offices, however I then get one way audio between extensions at different offices.

Office A (192.168.4.1)
Office B (192.168.3.1)

Both connect to the 3cx server in Amazon, everything works, however when a user from A calls a user in B and vice versa, we get one way audio. If I set the PBX delivers audio option to on this prevents the call transfers working between offices but fixes the one way audio.

ALG is disabled on both routers.

Thanks in advance,

Alex

 

[JohnS_3CX]

1. Since you are using STUN, there is always a higher possibility that something can cause problems. If you have two offices consider deploying an SBC at each office which will greatly improve the situation.

2. You can also keep using STUN, but it's highly advised that you read the below article and ensure 100% that all the requirements for STUN have been met. Also, be advised that there may be ALG on your ISP equipment (after your firewall) which you may not be able to disable if they don't allow you to. This can still potentially cause problems.

3. You haven't mentioned, but your Yealink firmware also needs to be the latest supported by 3CX
https://www.3cx.com/support/phone-firmwares/

4. W52H is a handset (not an IP phone) so it is not important. You also have a wireless Base (the equivalent of an IP phone) where the handset pairs, this is the important part that needs to also have the latest firmware (check model name on base).


Guides for setup and firmware on all supported Yealinks can be found here if needed
https://www.3cx.com/sip-phones/