iphone 拨打电话的API

今天在网上看到这个，先留着

+ (void) makeCall:(NSString *)phoneNumber
{????
????NSURL *phoneNumberURL = [NSURL URLWithString:[NSString stringWithFormat:@"tel:%@", phoneNumber]];
????NSLog(@"make call, URL=%@", phoneNumberURL);
????
????[[UIApplication sharedApplication] openURL:phoneNumberURL];????
}