Question marks have appeared concerning demand for Apple’s newest iPhones, after the company took the unusual step of omitting pre-order sales information from a press release detailing availability.

Traditionally, shortly before the full availability of devices, it issues a statement which, among other things, trumpets pre-order demand for the new smartphones.

For example, in September 2012, it said that “pre-orders of its iPhone 5 topped two million in just 24 hours, more than double the previous record of one million held by iPhone 4S”.

In October 2011, it said that “pre-orders of its iPhone 4S have topped one million in a single day, surpassing the previous single day pre-order record of 600,000 held by iPhone 4”.

And in 2010, it said that pre-orders of 600,00 had impacted its systems, “resulting in many order and approval malfunctions”.

This year, however, the company did not cite demand for its new iPhone 5c, which was available on pre-order. Its more costly sibling, iPhone 5s, is not available as a pre-order option at all.

According to Reuters, an unnamed US operator had said that demand for the iPhone 5c – which is a slightly cheaper unit available in multiple colours – has not been “overwhelming”.

And it also said that supply of the premium iPhone 5s – the company’s more traditional flagship refresh – is “disappointing”, an issue which has also affected the iPhone 5c.

The Wall Street Journal, meanwhile, said that China Unicom had seen pre-orders of more than 100,000 units for the latest iPhones – solid, but “sharply lower” than the 300,000-plus seen for the iPhone 5.

The introduction of the iPhone 5c and iPhone 5s marks a significant change in business model for Apple, which has previously offered a limited number of variants of its devices.

It now has to manage global supply of the iPhone 5c, which is available in five colours with two memory options, the iPhone 5s, which is available in three colours with three memory options, a version of the iPhone 4S which remains available in two colours, as well as different operator/regional variations of the portfolio.

Of course, the consumer-focused iPhone 5c is targeting mass-market consumers rather than Apple’s core devotees, who are most likely to be drawn to the premium iPhone 5s – which is not available on pre-order.

Until the devices reach full availability, and Apple announces firm details of iPhone sales following the launch, any analysis could be significantly flawed.

The iPhone 5c and iPhone 5s will be available this Friday (20 September) in the US, Australia, Canada, China, France, Germany, Hong Kong, Japan, Puerto Rico, Singapore and the UK.