Tap "Settings" from your iPhone's home screen.
Then scroll down a bit, and you will see the option "Show My Caller ID", click that.
Tap "Show My Caller ID" to toggle between "on" or "off." When off, your caller ID is blocked and people will not see your phone number when you call them.
This was very short, but it's nice to know how to do it on a iPhone, since many people don't even think that there's a option like that. Hope you like it. :-) Follow for more.
OBS. This only work if you have udated your iPhone to the newest version, i updated to 6.0.2, to check what update you have go to general - about - version. And to update: general - softwareupdate.