There are two ways to acheive this:-
1) [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://9912345678"]];
2) You can use the UITextView
and enable phone detection. After that the phone number will look like hyperlinked. Use the following code.
mytextview.text = @"9943586256";
mytextview.dataDetectorTypes = UIDataDetectorTypePhoneNumber;
mytextview.editable=NO;
Helpful if you want to show the phone number inside a custom tableview cell.
I would personally like the second one due to requirements in some project. When i have give the telephone number in UITextView
and upon pressing that will start the calling.