T43U still rings after the handset is picked up

[Alex100225]

Problem description:
the IP phone receives a call and rings. The handset is picked up. The phone keeps ringing. This doesn't happen to every phone call.

Yealink T43U
Running firmware: 108.87.0.16
Mode: router phone
Powered by a phone power adapter.

The phone is located behind TP Link Archer VR300 router. The router has ALG disabled as per the picture below:

The IP phone has got a DHCP-reserved IP address within 192.168.x.y/24 network. The router has also got port forwarding for ports 5060 and 5061 set up that end up hitting the phone's 192.168.x.y IP address:

 

[JohnS_3CX]

Hi Alex,

Remove the forwards please as these expose you to the entire internet unnecessarily - the phone does not use those ports when in router mode. It requires no port forwards period.

If you want to ensure everything is done right:

1. Upgrade the T43U using the 3CX supported firmware
2. Delete the phone from 3CX
3. Add it again as a router phone https://www.3cx.com/sip-phones/yealink-t4-series/
4. Finally factory reset it and wait for it to become a router phone automatically.


By the way, the phone's hook may simply be getting stuck when you lift the handset.
Next time this problem occurs, simply try pressing the Speakerphone button and see if the call is being answered immediately.
The guide I shared should cover everything you need.

 

[Alex100225]

I have replaced the phone with another of the same model, and it has undergone both a factory reset and a firmware upgrade. However, the customer reports that the issue is still present. Yes, they have attempted to use the Speakerphone button. Additionally, the customer has reported that the 3CX mobile app is experiencing the same issue.

 

[JohnS_3CX]

Understood, it sounds like this is not a phone issue then. You probably have to look at the internet connection on both ends including the side of the server, as well as the server specs.

If you think those are ok consider opening a Support Ticket for further investigation. You will need logging and captures to "catch" the issue as it happens.