iphone call programmatically

 NSString* telephone = @"tel:";
 telephone = [telephone stringByAppendingString:@"45345678"]; // set phone number
 NSURL *url = [ [ NSURL alloc ] initWithString: telephone ];
 [ [ UIApplication sharedApplication ] openURL: url ];

source: http://www.experts-exchange.com/Apple/Hardware/iPhone/Q_24182155.html