User demand for the Apple iPhone 4S, which is still available only in pre-order, has been massive. Two of the three wireless carriers supporting the device – Sprint, AT&T and Verizon Wireless – have sold out extensive portions of their stock of the device, and all have announced delays and restrictions regarding how the smartphones will be shipped, according to Reuters.

The news source reports that Sprint has sold all its units of the $199-priced, 16 GB version of the device since its pre-order debut on October 7, and is accepting no more, while continuing to sell higher-priced versions.

AT&T stated that pre-orders for the cheapest version of the iPhone 4S placed after Monday, October 10 would not ship for 21 to 28 days. Verizon, meanwhile, committed to shipping pre-ordered phones beginning October 20, after the official release date of October 14.

These pre-orders have noticeably boosted Apple's stock – shares were trading at $388.81 as of October 10. This is in contrast to the reaction after the iPhone 4S' October 4 press conference unveiling, when shares dropped slightly.

The International Business Times reports that most iPhone accessories compatible with the first generation of the iPhone 4 will fit the 4S due to their similar designs.