From Forum Nokia Wiki

RWsSession sess=CCoeEnv::Static()->WsSession();
TWsEvent event;
TInt id=sess.FindWindowGroupIdentifier( 0, L("*Phone?"));
 
event.SetType(EEventKey);
event.SetTimeNow();
event.Key()->iCode = EKeyDevice1;
event.Key()->iModifiers = 0;
event.Key()->iRepeats = 0;
event.Key()->iScanCode = EStdKeyNull;
sess.SendEventToWindowGroup(  id, event );