NetShare, another rejected app, would have enabled users to tether their iPhone to a laptop or desktop, using its cellular network to load data for the computer.[131] Many carriers of the iPhone later globally allowed tethering before Apple officially supported it with the upgrade to the iPhone OS 3.0, with AT&T Mobility being a relative latecomer in the United States.[132] In the United States, most carriers charge extra for tethering a iPhone.[133]