Phones continue to ring after call hits voicemail

[Blake Carter]

I have a 3cx system running 15.5.15502

The phone server runs the phones for 2 locations (connected by site-to-site VPN, sonicwall).

The server sits in the subnet 10.1.0.1/23 (dhcp controlled by dhcp server)
The problematic phones sit in subnet 10.3.1.0/24 (dhcp controlled by sonicwall)

All phones are Yealink T29G with latest firmware.
Phones at both locations are setup as local lan

Whenever a call goes to an extension at the 10.3.1.0 location even after the caller disconnects or hits voicemail the phone will continue to ring and ring and ring until someone picks up the receiver. I recently installed the latest firmware on the phones and rebooted them and it resolved the issue for a week or so, now it is back. Happens with both internal and external calls.

I have watched from the dashboard and the call is not getting stuck in the active calls as it shows it disconnecting when the caller hangs up so I am not sure what is going on here.

Anyone have any suggestions on where to start?
Should the phones at the second location be setup as Remote Stun since they are not on the same subnet as the server? Would assigning the server a 10.3.1.0/24 address as well as the 10.1.0.0/23 address resolve this issue? Should be able to fully route between subnets. The 2nd location uses applications and accesses file shares from the primary location and all of that routing works correctly.

Any help is appreciated.

 

[Saqqara]

First thing, I would update to the latest version 16 update 4 if you have a valid maintenance contract. You are running a older version, and will have issues later down the line with licensing , etc

As you have a site to site vpn, you configure the phones as local. The remote location to the 3CX server, setup dhcp with option 66 - https://www.3cx.com/sip-phones/dhcp-option-66/

 

[JohnS_3CX]

Hi Blake,

Firstly, I would recommend to upgrade to V16

Then for the specific issue, it sounds a bit like the phone receives the invite, but it doesn't receive the message to stop ringing. I'm guessing this is due to something happening on your network. I imagine that if you were to bring one of those phones to the other site, the issue would stop. The file shares working are not an indication that the phones should also be working.

You can either run a bunch of captures on the PBX and phones simultaneously to verify this and then spend time on your networking to sort it out, or you may benefit from using a SBC if you are unable to traverse the network correctly (with V16)

 

[JohnS_3CX]

I should also point out that the firmware release for the T29G on V15.5 is different to the one on V16.

 

[Blake Carter]

I went ahead and upgraded the system to V16 and pushed the latest corresponding Yealink firmware to the affected devices. We'l see if this corrected the issue on Monday.

 

[Blake Carter]

After updating to V16 with latest patch and upgrading yealink phones to latest firmware this is still happening.

 

[JohnS_3CX]

Hi Blake

I would suggest to run a capture on the PBX, and at the same time run a capture from the phone's UI, and then analyze the captures in wireshark.

Capture A:
You should see the PBX sending a SIP message to the phone IP telling it to stop ringing when the appropriate time comes.

Capture B:
You should also see the the message received on the actual phone.

I would confirm this before anything else, because if the PBX sends it and the phone does not receive it, then something may be wrong on the network and could justify this phenomenon. Perhaps the captures may show something else happening too (depending on whether its a RG, queue, or direct call), that can at least hint towards what the cause is.