ios - CTCallCenter callEventHandler is never called -

i try use ctcallcenter receive incoming call iphone. while application active call device , nothing happens calleventhandler not invoked.

what can reason?

i use ios9.0 beta3 installed on iphone 5 , xcode7.

my code:

- (void)viewdidload { [super viewdidload];  ctcallcenter *callcenter = [[ctcallcenter alloc] init]; callcenter.calleventhandler = ^(ctcall* call) {     if (call.callstate == ctcallstatedisconnected)     {         nslog(@"call has been disconnected");         [self showmessage:@"call has been disconnected"];     }     else if (call.callstate == ctcallstateconnected)     {         nslog(@"call has been connected");         [self showmessage:@"call has been connected"];     }     else if(call.callstate == ctcallstateincoming)     {         nslog(@"call incoming");         [self showmessage:@"call incoming"];     }     else     {         nslog(@"none of conditions");         [self showmessage:@"none of conditions"];     }   }; }