Freepbx feature question

I´m a newbie in freepbx, and I would like to know if is possible that to set a scenario like this:

I have some sellers with their cellphones. I would like to give they a number to call and when they call, before system pick up, freepbx get callerid, hang up and then callback.

But I want to do a callback through voip line, and give they a tone to call to a desired number.
If what I want is possible, then I should use two lines? one for callback and other to give a tone? or I can use just only one voip line with conference enable?

I hope that someone can help me.