iPhone 4S pre-orders on all three U.S. carriers have sold out. Apple recently announced that it had sold a record-breaking 1 million iPhone 4S units over launch weekend, with AT&T accounting for 200,000 of those orders.

After the first day of pre-order availability, shipping estimates fell worldwide to 1-2 weeks. Those that were fortunate to pre-order before stock ran out will have the iPhone 4S delivered tomorrow.

Bloomberg reports:

“Verizon Wireless, the largest U.S. wireless operator, and Sprint, the third-biggest, showed no immediate stock of iPhone 4S 16-gigabyte models for pre-order on their websites. AT&T, the No. 2 carrier, is giving buyers on its site a delivery estimate of three to four weeks, up from one to two days when pre-orders began Oct. 7.”

The iPhone 4S goes on sale officially tomorrow in stores, and all three carriers have sold all pre-order stock. There will be a select amount of units available for purchase tomorrow at Apple stores and partner retail chains, but these reserved units will only be available for the first customers in line. (Heads up: People are already in line.)

While harsh criticism said that the iPhone 4S was a huge disappointment, sales have shown the opposite. The iPhone 4S is looking to be Apple’s best-selling iPhone yet.