Apple is all set to take in old iPhone models and give consumers $US200 credit for their next device purchase, triggering rumours that the tech giant is on a high gear for the anticipated iPhone 6 and iPhone 5S release date.

According to Bloomberg, work is underway for a new sales promo that would allow iPhone owners to surrender their iPhone 4 or iPhone 4S and get the iPhone 5 with a contract virtually free of initial payment.

In a similar program with AT&T, the rebates go as high as $US200 but it remains unclear if the same model will be applied in the new Apple promo that involves the tech giant's bricks-and-mortars outlets in the United States.

Yet with Brightstar, the same firm tapped by AT&T to run its in-house iPhone trade-in scheme, the chance is high that the two programs will be governed by identical offerings.

This is the first time that Apple Stores will be directly involved in sales promos that focus on Apple's flagship smartphones, according to Apple Insider.

The program, the report added, will be mutually beneficial for the tech giant and its millions of customers. For the latter, they can avail of iPhone discounts will less hassle and minus third-party participation.

For Apple, the object is obvious - to shoot up its U.S. sales in dramatic fashion in light of tightening competition, chiefly coming from Samsung's Galaxy S4 that so far has collected over 10 million of global sales.

It remains unclear if the upcoming Apple deal will run a long course and overlap with the expected iPhone 5S release date that analysts said will take place in September or even as early as August.

Or even long enough to benefit the multitude Apple hold outs, who might want to wait out a bit more and go instead for the rumoured phablet-size iPhone 6, which Apple has reportedly programmed for a June 2014 release.

Reports have indicated that the iPhone 5S merely represents incremental improvements but new killer features such as fingerprint sensor, capacitive home button with sapphire coating and NFC-enabled wallet payment.

It is the iPhone 6 that will come with the major bump ups - likely among them are wrap-around screen display that stretches 4.8-inch on each side and invisible or disappearing control keys, including the iconic Home button.