Sources at US networks speaking to AllThingsD have warned that inventories are far lower than what they had expected.
“We will have grotesquely unavailable inventory,” one network source told the site. Another called shipments “extremely disappointing”.
Apple’s bricks and mortar stores are also likely to be short on stock. According to reports, around 70 to 80 per cent of new iPhones are sent to Apple’s own stores.
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However, if supplies are as low as networks have alluded to, they may also be low there too.
The second source is reported to have said that while stocks are much lower than expected, demand is also down. Much of that is down to the popularity of the iPhone 5c.
Apple has remained quiet on the issue of iPhone 5c pre-order numbers. However, despite higher demand for its colourful model, it does not appear it will sell out.
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The official Apple store still says it is possible to order one and have it delivered on launch day.
Both the iPhone 5s and the iPhone 5c are officially launched on Friday. iOS 7 is due to be released later today. Based on previous updates, availability notifications will likely go out around 6pm.