[asterisk-users] Attended transfer problem

[jg]

I have a setup where there are occasional problems with attended transfers. I have already 
checked the devices as well as the relevant DTMF modes (SIP INFO and rfc2833). I could not find 
any problems here.

The setup is a follows:

The front desk (F) accepts calls from customers (C). In some cases F needs to transfer C to a 
specific department (D). If D cannot handle the problem, D tries to transfer to a specialist S. 
The problem sometimes occurs when D tries an attended transfer for C to S. The description I 
have so far is that Asterisk sometimes does not seem to accept DTMF signals.

Is it conceivable that that this is a re-INVITE/directmedia problem?

Since I have only limited access to the system, I'd like to rule out some causes. I am also not 
sure if the transfer from F to D is handled via Asterisk using DTMF signalling, or whether F 
uses the SIP phone's capabilities for the transfer, so that Asterisk might already not know 
anything about D. Except for C, everybody is inside the same subnet.

jg