Sprint and AT&T, two U.S. carriers of the iPhone, have asked their employees to work overtime hours to handle the expected rush when Apple launches its new version Tuesday.

The telecoms, along with Apple, had earlier barred employees from taking time off this month to prepare for the much-awaited launch.

U.S. consumers can now choose Verizon and Sprint, as well as the original carrier AT&T, got their iPhones.

Sprint is still amending parts of its customer policies for the selling of the iPhone 5 in the coming weeks. But Apple is yet to confirm if there will be a Sprint iPhone 5 in the market. The confirmation is expected at Tuesday's unveiling at the Apple campus in Cupertino, Calif.