The moment iPhone 4S was unleashed upon the world – to record sales, no less – it was guaranteed the rumour mill would turn its attention to the roll out of its successor.

However, supposed revelations surrounding a potential summer 2012 release for the next iPhone have, according to multiple sources, lifted the lid on iPhone 4S's back story - a device, it's claimed, previously designed to compliment iPhone 5's launch, rather than replace it.

Dual strategy

To cut a long story short, both CNET and 9to5Mac claim Steve Jobs spent most of 2011 working on iPhone 5, while iPhone 4S and iOS 5 were originally pencilled in for an unveiling at WWDC in June.

However, while iPhone 5 was actually moving forward ahead of schedule, problems with Siri meant iOS 5 wasn't likely to be ready until mid-October.

An attempt was made to speed up the development of Jobs' iPhone so it would it could launch alongside iOS 5 this autumn. If it could be readied in time, iPhone 4S – itself essentially ready to go at this stage – could be launched alongside it as a budget model.

"Along the way, there was pushback from Apple's partners at [iPhone manufacturer] Foxconn," reports 9to5Mac.

"Foxconn obviously did have prototypes of the iPhone 5, but it turns out that building the iPhone 5 in necessary yield rates couldn’t be done in time for a holiday 2011 release."

Plan B

Indeed, by early September it was clear iPhone 5 wasn't going to be ready in time, with iPhone 4S instead stepping up to the plate to be billed as the genuine successor to iPhone 4.

If early sales are anything to go by, it's a strategy that's worked out well for Apple, delivering a boost in sales over the Christmas period and also handing new CEO Tim Cook a device that can easily be repositioned as a budget handset when iPhone 5 does eventually roll into town.

However, the one concern for those currently signing up for 12 or even 24 month contracts to get their hands on an iPhone 4S is 9to5Mac's claim Apple still plans to launch iPhone 5 this summer.

It appears Jobs' last project as Apple CEO could be set to hit the shelves entirely out of sequence with 4S's debut.

[source: 9to5Mac]