Apple’s keenly awaited new iPhone flew off the shelves after making its United States retail debut on Friday night, selling an estimated 200,000 handsets.

Most of the nearly 2,000 designated sales outlets sold out within hours.

AT&T, the exclusive network operator for Apple’s mobile phone, iPod and web-browsing device had sold out of iPhones at most of its 1,800 stores by Saturday morning, although its staff continued to take orders over the weekend for the $499 (£248) device.

Some buyers had problems activating the phones because the large number signing on to AT&T strained the network.

Apple would not say how many devices it had sold, but industry analysts suggested that Apple stores sold 128,000 and AT&T’s outlets 72,000.

EBay, the online auctioneer, said that customers had sold 745 iPhones within 24 hours of the launch, with one being offered for as much as $10,000.

However, when the fanfare has died down, the real test will begin.

Apple’s shares have jumped by nearly 50 per cent since the first prototype was unveiled in January, adding about $34 billion to its market value.

The question that analysts are asking is whether the shares have peaked or whether the sky is the limit.

Roger Kay, president of Endpoint Technologies, an American consultant, said: “This is undoubtedly an inflection point, a very risky moment, and things could go either way.

"Expectations are high and will be extremely difficult to fulfil, potentially leading to considerable disappointment. But the phone could prove so engaging that it will not only sell tremendously well but also bring new people to Apple’s other products.”

The zealous initial buyers of the iPhone, some of whom had queued for days before Friday’s 6pm launch in the United States, were — predictably — delighted with the device, but it remains to be seen to what extent the phone’s undeniable qualities, such as its beauty and versatility, outweigh pitfalls, such as the slow internet hook-up, the non-replaceable battery and the minimum $499 price.

Meanwhile, the iPhone initially will operate only on the AT&T network, which means that people currently with rival operators will have to pay hefty fees to buy themselves out of their existing contracts.

In areas where AT&T’s coverage is poor, the absence of an alternative operator means that they will have no choice but to persevere.

Analysts expect a 3G version of the phone to be launched early next year, which would clear up the internet issue, and it may include a removable battery, but price is almost certain to remain an issue.

The cheaper $499 model is eight times the price of the average mobile phone and 2½ times the cost of a high-end one.

Analysts are divided as to how many iPhones Apple will sell. The most bullish suggest that it may shift as many as 45 million over the next two years; the bears say it may be as few as eight million, less than 1 per cent of global handset sales.

Kevin Hunt, an analyst for Thomas Weisel Partners, forecasts that Apple will sell about five million iPhones in its current financial year, to September 30, and about 18 million in the following financial year.

That would very roughly meet Apple’s own forecasts of selling ten million phones in the next 12 months, which would bring in $5.5 billion of revenue, assuming that an equal number of $499 and $599 phones were sold.

This would give a boost to the bottom line of Apple, which had sales of $19.3 billion in its last financial year, to September 30, 2006, on sales of products such as computers and iPods and of music, through its iTunes music website.

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