Apple's new iPhone 5S and 5C were met with lukewarm response when the handsets launched at the company's keynote media event last month. However, Apple has still sold millions of handsets since the event, and the sales figure remains high. The gold iPhone 5S has been sold out everywhere, with new stock not available until November or later.

Fans were mostly hoping for a design overhaul for the flagship iPhone 5S smartphone, with a bigger screen to compete with other Android brands, but were left disappointed when the display size remained at 4 inches.

Apple revamped its flagship iPhone 5S with an upgraded A7 chip, all new M7 processor, and a fingerprint sensor.

Rumors for the next-generation iPhone 6 have already started despite many customers still waiting to receive their new iPhone 5S.

The iPhone 6 is rumored to pack a screen size comparable with its competitors. While some rumors state that the next-gen phone may pack a screen as big as 6 inches to compete with the Samsung Galaxy Note 3, many believe it will be upgraded to a 4.8 display.

It is also expected to feature a massive 128 GB storage, double the size of the maximum storage offered on the iPhone 5S. The screen may also feature the Sharp IGZO technology, and NFC (near field communications) technology, which is available on Samsung Galaxy devices. It may also be upgraded with an A8 chip and be offered in the surprisingly popular gold/champagne color as well.

Rumored release dates for Apple's iPhone 6 points to a launch in the Spring of 2014 – possibly in March.