Answer

You cannot programatically dial an number using the iOS SDK.

However, if you use the tel link to invoke the iPhone Phone application to dial out a number.

Example :

To dial 288-222-8717

pass the following string to the iphone phone app as

tel:2882228717

 NSString *phoneUrl = [NSString stringWithFormat:@"tel://2882228717"];
            [[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneUrl]];