[Asterisk-Users] Anyone already pionered outing calling with user selcted background noise?

[magnus]

Hello,
We are at the beginning of an asterisk project to be able to have callers
call in on premium rate number, (Which funds outgoing call) be presented
with ivr menu choice of background noises, then be presented with external
dial tone, outgoing dialled digits collected and then dialled and once
connected, background music invoked as well as connecting original caller
and dialled person. For example, guy's late home, needs an excuse, wants to
call home and "pretend" his flight is/was delayed, thus he would dial in,
select airport background music with canned tannoy recording of flight
delays and then enter his home telephone number. Or variations of theme. 
We think it can be done with Asterisk, simple IVR, E1 Zap channels, but
thoughts on how would we mix canned selected audio file and outgoing call?
Input from anyone's that's tried this welcome.
Thanks
Magnus