Sometimes cannot "join" call

[Mister VoIP NL]

Hello,

I have a self hosted 3CX system v18 Update 7 (build 312) with users who
are using the 18.12.425 version of the Desktop App.

Multiple times a day this strange thing occurs, but not with every call:

They want to transfer an incoming call
Choose attended transfer
The other person picks up the call
The original caller cannot choose to join the call (it's greyed out)
And cannot return to the original caller
When she disconnect the line seems to be transferred but cannot be picked up

The error message in the 3CX activityu log says this:

05/22/2023 4:17:55 PM - L:6680.1[Line:10000<<+4012345678] failed to reach Extn:209, reason Busy

But the extension is not busy. Anybody any idea what could cause this?

Thanks in advance

 

[JohnS_3CX]

Hi,

If this attended transfer was done to an external number and you heard audio but the "Join" button did not light up then the provider (or whatever destination you reached up to that point) probably connected you with early media (SIP 183 Session Progress message).

 

[Mister VoIP NL]

Hi,

If this attended transfer was done to an external number and you heard audio but the "Join" button did not light up then the provider (or whatever destination you reached up to that point) probably connected you with early media (SIP 183 Session Progress message).

Hi John,

Both are using the Desktop app, i'm going to test by letting them use the webclënt PWA. I'm starting to think it's a network related issue because the person who they are transferring to cannot answer calls sometimes.

Regards

 

[JohnS_3CX]

That may indeed be the case - if the call answering is not properly acknowledged that could also happen yes.