Yealink T54W BLF/Extension In Use problem

[eagle37]

We are using Yealink Desk phones, model T54-W, currently running Firmware version 98.86.0.45.

We have been experiencing a random issue with extensions showing available when they are actually busy. I don't really know exactly how often it happens because I don't see any issues with that extension in the 3CX logs to draw attention to the problem (Maybe I'm looking in the wrong log?) Currently, my only way of knowing it's happening is manually comparing the desk phone BLF for the extension in use to 3CX and possibly physically knowing the extension is in use if both statuses are wrong (This was in v16, not v18, yet). Latest call example I have was yesterday afternoon.

So far I've been able to determine that this is happening whether:
1. the extension is local or remote
2. the extension is using the desk phone or the 3cx smartphone app
3. all examples seem to be inbound calls. I have not yet found an outbound call example
4. it's happened on transferred calls, calls directly to an extension, and calls through a ring group
5. the problem has existed in the last several versions of v16 and v18. I used to find that the status was wrong in 3CX and on the Yealink desk phone in v16. In v18, I have not yet found the wrong status in 3CX, only on the desk phones, but we've only been using v18 for a couple months.
6. the problem has existed in the last several Yealink firmware versions

Has anyone else experienced this? Any troubleshooting thoughts?

Thank you

 

[Alphabetic]

When you say busy do you mean the status is busy or they're on the phone?

 

[eagle37]

When you say busy do you mean the status is busy or they're on the phone?

The extension is in use, but the desk phone BLF status shows available.

 

[JohnS_3CX]

Hi,

Is your T54W provisioned as STUN / SBC / LAN?

Is it connected on LAN cable or WiFi?

 

[eagle37]

SBC. LAN Cable.

 

[eagle37]

SBC has been updated to Debian 10, as well, and problem existed with the old and new versions of the SBC.

 

[JohnS_3CX]

The BLFs monitor call state: Idle / Ringing / Busy

This is sent from 3CX --> SBC --> Phone

Assuming that the SBC is running on the recommended hardware (ie. not overloaded) and assuming that the internet connection of the SBC does not have any loss, then normally you should be able to see the call state change immediately (1 sec. maximum)



You might want to take a look at these stats to see if there is any loss on SBC


What hardware spec is the SBC machine?

 

[eagle37]

The BLFs monitor call state: Idle / Ringing / Busy

This is sent from 3CX --> SBC --> Phone

Assuming that the SBC is running on the recommended hardware (ie. not overloaded) and assuming that the internet connection of the SBC does not have any loss, then normally you should be able to see the call state change immediately (1 sec. maximum)

View attachment 27125

You might want to take a look at these stats to see if there is any loss on SBC
View attachment 27126

What hardware spec is the SBC machine?

8 active extensions
Running HyperV with SBC Guest on it's own dedicated LAN port
CPU is regularly less than 1% usage, 2 VPCs
2GB RAM, 1.5GB free
RAID 10 SSD 40GB disk space, 3.32GB used
SBC is on the same VLAN as the desk phones
OS is Debian 10 from your latest ISO, but also existed on the prior Debian installation
Where do I find the RTP packets received/lost?

 

[JohnS_3CX]

Running HyperV with SBC Guest on it's own dedicated LAN port

Very Important - please install NTP as per this article here. Hyper-V is known to have time drift, and this is enough of a reason to affect BLFs and registration. https://www.3cx.com/docs/installing-microsoft-hyper-v/#h.cjj20zk71lns
Let me know please if the situation improves after installing NTP

Where do I find the RTP packets received/lost?

Go to SIP Trunks, click your SBC then click the statistics tab

 

[eagle37]

Thank you - I installed NTP on the SBC. Do I need to install on the 3CX server, also?

The SBC stats showed 0% loss, but I didn't get the screenshot before I installed NTP and the counters reset to 0% - sorry.

 

[JohnS_3CX]

You are welcome!

So you only need to install it on any machine that runs under Hyper-V specifically.
If 3CX is on Debian via Hyper-V then yes. If not, then no do not install it on the 3CX Server.

No problem if the counters were reset, just monitor it for a couple of days and I feel confident that this should reduce the problem greatly, if not completely.

 

[eagle37]

thank you!

 

[eagle37]

3CX is running on Hyper-V, so I installed NTP on that server, as well. Do I need to reboot or restart any services?

 

[JohnS_3CX]

Nope, if it is running fine leave it as is. The NTP service should start running immediately after you installed it.