I have a specific call scenario where I want to transfer a call and have the destination (REFER-TO) end answer automatically. Basically I own both devices and I am moving the call from my mobile VoIP client to my SIP deskphone. I want it to be seamless with no ringback or alerting introduced (hence the reason I am looking at auto answer).

My SIP deskphone supports auto-answer when the Call-Info header indicates "answer-after=0". This header is specified in the REFER from the originating device (mobile VoIP client). Freeswitch does not pass this header through to the destination device.

Is there any specific setting that I can do to pass this header through? I know that I can change the dialplan using the following:

<action application="export" data="sip_auto_answer=true"/>

But this triggers all calls to the destination to be auto-answered. I only want some of the calls to be answered (hence to reason I want the originator to specify this header). 

Regards,

Peter