iPhone Make Call from App

OK .. i find the solution to iPhone Make Call Programmatically

//tell will take your telephone numbers or may be you can 
//pass the phone number variable to it too.

    NSString *prefix = (@"tel://1234567890");
        UIApplication *app = [UIApplication sharedApplication];
        NSString *dialThis = [NSString stringWithFormat:@"%@", prefix];
        NSURL *url = [NSURL URLWithString:dialThis];
        [app openURL:url];

Where to write this code.

I'm creating an XHTML application. Application needs to make call to a specific number when user clicks a particular button.

Please suggest on how to do this. I'm new to this.

Thanks in advance.

I WANT TO MAKE CALL FROM APPLICATION TO APPLICATION LIKE SKYPE.....GIVE ME SOME SUGGESTIONS.....

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://9909090909"]];

NOT like this......

this is way to call to app to iphone ....

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://9909090909"]];

NOT like this......

this is way to call to app to iphone ...

i need to call like skype ... free call on application nat phone number