Mark or classify outbound call

[srthomas]

Hi,

My customer uses Aastra handsets and they would like to "book" outbound calls to clients. Does anyone know a way that they can mark each outbound call they make with an id so when they get the break down of calls from us, they can on bill to their clients as appropiate?

Some kind of aastra XML app I guess but does it have a way to id the current call??

All ideas and help appreciated...

Steve