[Asterisk-Users] callback on busy

[Bartosz Jozwiak]

Hello everybody,

I would like to implement "callback" function.
When I call a person and his extension is busy I can press, for example, 5
and get a callback when his phone is not busy anymore.

When I create a call file and copy it to spool call folder
asterisk makes a call. One problem is that when extension is still busy
my phone rings and I get busy tone of the person who I am trying to reach.

Is there another way to do it ? Or do I need to check first if channel is 
free or
still busy ? Can anybody give me some hints ?

thx in advance.