[Asterisk-Dev] Supervised transfer / 3-way calling

[Eric Bart]

I've done some work. It is still being written ...

The consultative transfer should work for each phone.

Here's an old presentation :

New application for asterisk : axra

axra runs separately. developped in C++. it dialogs with 
asterisk through agi calls and through the manager api. 
it proccesses phone calls through the dial plan (agi) and 
concurently through the manager api.

axra currently provides consultative transfer for SIP and IAX2 
phones. this should easily be extended to any phone technology. 
hopefully, axra will soon provide 3 way calling.

there are two tranfer functions : PreTransfer and CTransfer
each should  be implemented in the dial plan like :
exten => 76,1,AGI(axraagi|PreTransfer)
exten => 76,2,Hangup
exten => 77,1,AGI(axraagi|CTransfer|auto)
exten => 77,2,Hangup

you may choose other extensions than 76 & 77. you may omit 'auto'

when a call is transfered to PreTransfer (76), the call is parked and
waits for a transfer. if the timeout occurs, the call is ringed back.
if you call PreTransfer (76) directly, the parked call (if any) is
immediatly ringed back.

when a call is transfered to CTransfer (77), the call is linked to
the pretransfered (parked) call. if no pretransfer exists the call 
is pretransfered just like 76 was dialed. however, if 'auto' was 
specified, axra will try to link the call to the oldest live 
channel attached to transferer's phone.

http://byortek.com/asterisk/