Transfer Issue

[Mr_F]

Hi there,
We have an issue with transferring calls, internal calls work great but when an external call comes in and we try to transfer this call to an internal or external number the originating call is left on hold.

If the external call rings in and is then transferred but the swap button is pressed twice and THEN transferred the call completes as normal.

Using Yealink T42S on latest firmware, multiple calls option is enabled and have tried using use PBX Audio which makes no difference.

Any help would be greatly appreciated

 

[Mr_F]

UPDATE:
We have narrowed this down to a Yealink phone issue, A spare Fanvil phone works correctly.

We have also narrowed the conditions down on the Yealink phones to
"Attended transfers fail, Blind transfer works on the Yealink, only fails on an incoming external call to and Internal being transferred to another Internal Number."

We do have two interfaces (One for SIP traffic)

 

[JohnS_3CX]

Hi @Mr_F

Are you using the default 3CX firmware and templates or custom ones?

If you are on V16SP1 your T42S should be on firmware level 66.84.0.35 and the template version should be:

 

[Mr_F]

Hi there,
Yes firmware version is 66.84.0.35 (Which is latest) and the template is the latest default with version 88608

Thanks

 

[JohnS_3CX]

How is the phone provisioned, and what type of connection is there between phones and PBX? (Local/STUN/SBC) ?

 

[Mr_F]

These phone are Auto Provisioned and Local (no STUN or SBC)

 

[JohnS_3CX]

Which trunk provider are you using or are you on a PSTN gateway?

Under your trunk's options do you have "Supports Re-Invite & Support Replaces" enabled?

 

[Mr_F]

Trunk provider is spitfire (spitfiretsp.net)
Trunk options enabled is Supports Re-Invite (Support Replaces is not as per specified trunk config)

With support replaces enabled as soon as the call is transferred the call abruptly ends

 

[Mr_F]

UPDATE:
a packet capture shows the call as being completed

 

[JohnS_3CX]

Hi @Mr_F

Does the audio stream in the capture from the provider stop though? If the phone does what it should and then how did you ascertain that the phone is the issue?

 

[Mr_F]

We ascertained it was a phone issue as a softphone and a Fanvil desk phone transferred the call as expected.

The audio stream in the capture seems to drop when the the user initiates end call (all they hear is the onhold music)