While the iPhone 6 has been made available for pre-order last Sept. 12, not all customers who anticipated the phone's release had been able to gain access to the online Apple Store. Numerous fans reportedly faced delays in placing their orders, including those who had been hoping to preorder the iPhone 6 Plus in carrier websites such as Sprint, T-Mobile and AT&T.

A spokesperson for Apple stated that the iPhone 6 and iPhone 6 Plus had broken their current sales records, although the number of phones sold was not made known.

"Response to iPhone 6 and iPhone 6 Plus has been incredible, with a record number of pre-orders overnight. Pre-orders are currently available online or through the Apple Store App," spokeswoman Trudy Muller stated.

As such, the iPhone 6 and iPhone 6 Plus have been deemed as the bestselling models for the iPhone series.

With the largest pre-sale launch in Apple history, the 5.5-inch iPhone 6 Plus went out of stock only hours after pre-orders were announced on launch day both on the online Apple Store and through mobile carriers. While the 4.7-inch phones were reportedly pushed back by seven to 10 days, the 5.5-inch models have been said to be delayed by three to four weeks for Verizon Wireless, Sprint and AT&T.

According to AT&T, the mobile carrier has already reported its biggest pre-order sales record with the launching of the iPhone 6 phones.

"This is our biggest iPhone pre-order launch day ever," AT&T Mobility CEO Glenn Lurie stated last Friday.

Pre-orders for both the iPhone 6 and iPhone 6 Plus will start on September 19 at midnight for several countries, including the U.S., U.K., Canada, France, Germany, Australia, Singapore, Hong Kong, Japan and Puerto Rico. For a two-year contract among U.S. customers, the iPhone 6 will come at $199 for 16GB, $299 for 64GB and $399 for 128GB. For the iPhone 6 Plus, a two-year deal will offer a price of $299 for 16GB, $399 for 64GB and $499 for 128GB. 

For the U.K., the two variants can be obtained through O2, Virgin Media, Vodafone, EE, Three, Phones4U and Mobiles.co,uk. The Apple Store is also offering unlocked iPhone 6 handsets at £539 for 16GB, £619 for 64GB and £699 for 128GB. The iPhone 6 Plus will come at £619 for 16GB, £699 for 64GB and £789 for 128GB.