[INFO] Yealink T58V and my VOIP provider ...

[Marari]

3CX V15.5.13103.5
Yealink SIP-T58V firmware: 58.80.0.65
Google cloud hosted PBX
Phones are served by an SBC

I have one Yealink T58V on the network. The rest are T29G or T42s. When using the Yealink T58V and dialing out, the call would often fail on the primary trunk and sometimes on the secondary. If the call actually managed to go through, it would take over 30 seconds (for the 30 second timeout on the primary trunk to fail over to the secondary). No other phone on the network has this problem.

After pouring through logs and working with the VOIP provider (VoiceMeUp), it appears as though the T58V was creating a fragmented invite and pushing SDP to a large frame.



But WHY?

Answer: The video module on the T58V.

If the module is plugged in, the phone adds the video codec bumping the frame to something bigger than the VOIP provider could accept and fragmenting the invite before timing out and moving to the secondary trunk.

The solution: Either remove the USB video module from the T58V (effectively making it a T58A) or simply disallow video calls in the trunk options. Both seem to work... so far.

 

[eddv123]

Interesting....

It would be good to see what the response from the provider is as well and also whether using another providers trunk as a test works or not (I may test this myself in fact).

Despite the fact that they are a supported/preferred provider for you guys in Canada this would have no bearing as it is all about the capabilities of the trunk and what the Yealink sends:
https://www.3cx.com/partners/sip-trunks/canada/

 

[YiannisH_3CX]

Hello @Marari

Thank you for sharing your findings with the forum. I am sure the information will be useful to many people using these phones. You could also try removing either video codecs from the phone or unused audio codecs from the extension to prevent the Invite from becoming to large and see if that works.

 

[Marari]

Interesting....

It would be good to see what the response from the provider is as well and also whether using another providers trunk as a test works or not (I may test this myself in fact).

I really do have to give huge kudos to the VMU support team. They are heads and shoulders above any support I've ever received from a 'traditional' telco.

Their response was pretty much what you see above. Incorporating a bit of @YiannisH_3CX response as well. Essentially, turn off all unused codecs. I took it a step further by disabling the camera on the T58V to find out if that was the culprit (it certainly was a good part of it), but in the end, I saw no difference between disabling the camera itself and simply turning off Allow Video Calls.