iPhone 6 release date may occur anytime soon as reports claimed millions of iPhone 5C units were still unsold.

According to Digitimes, more than 3 million iPhone 5c units are waiting for buyers, of which two million units are stored in Pegatron's warehouses, while one million units are collecting dust in carriers' and retailers' shelves.

Previous reports revealed iPhone 5S was the real winner among the 2013 iPhone models that Apple came up with. The low cost iPhone 5C failed to attract iPhone consumers yielding to poor sales and profits.

"Due to their contracts with Apple and high purchasing prices, most telecom carriers and retailers are unlikely to offer significant price cuts in the short-term for the iPhone 5c. Currently, iPhone 5c is priced at US$99 (16GB) and US$199 (32GB) with 3G service bundle plans, and US$549 (16GB) and US$649 (32GB) for the smartphone itself, the sources noted," Digitimes wrote.

Some consumers believed iPhone 5C failed to prove that it is a cheap iOS device. But the tables could turn when carriers and retailers drop the existing prices to clear the remaining inventory once the iPhone 6 will be released.

iPhone 6 release date was set to arrive as soon in September this year. The reports said iPhone 6 release date will follow last year's launch of iPhone 5S and iPhone 5C.

Consumers can expect the iPhone 6 around September or October, according to iDigitalTimes. It was previously reported iPhone 6 will be released in June at Apple's Annual Worldwide Developers' Conference alongside the upcoming iOS 8.

Rumors also claimed two iPhone 6 will be coming this year and both versions will come with a bigger screen display. One of the new iPhone variants was speculated to enter the phablet category as one of the variants with 5.6-inch screen panel.

Also, reports claimed iPhone 6 will pack faster and better A8 processor, and the upcoming iOS 8. iPhone 5S' touchID fingerprint sensor will surely receive new features and improvements.