Take a look at http://doc.trolltech.com/4.3/uitools...heritance.html

It should be possible.

However if 'onIncomingCall' is indeed a slot, then you have to make ICallHandler derive from QObject. If ICallHandler will only be used with Qt apps, then that should be ok. If not, you could use the boost signal/slot library or build your own framework for this.

HTH