asterisk users - Aug 2006 - Attended Transfer call return with asterisk + sipura spa2002

Hi!

I have connected my analog phones to an asterisk box with sipura spa2002
devices.
I can do an attended transfer by taking the call which should be
transferred, pressing the flash button, dialing the number to which the
call should be transferred and now i can hang up or talk to the person
who receives the transferred call.

Thats working perfectly.

But if the other person (the person who gets the transferred call) isnt
on his place and doesnt take the call, the call gets disconnected after
about a minute.

Does anyone have an idea how i could make that the call gets transferred
back (to the person who initially did the transfer) automatically?

thx,
Tom