While some analysts expect the new phone to sell best in the United States and Western Europe, consumer excitement in new markets such as Hong Kong, Japan and New Zealand appeared to foretell strong demand in other markets too.
"The key is less likely to be demand and more likely to be supply," said Atlantic Equities' Cordwell.
In Hong Kong, Hutchison Telecommunications was flooded with 60,000 online applications over the weekend from consumers hoping to buy the 500 phones on sale there.
In New Zealand, which will be the first country to sell the phone due to its time zone, people started lining up outside a Vodafone store on Tuesday, according to a local paper.
02, the UK arm of Telefonica, said its website was overwhelmed with early orders on Monday after being hit with 13,000 orders per second during the peak, according to a spokesman who said it had sold out in a few hours.
The carrier, which is giving the phone away to customers who commit to specific data service packages, said it has stock left to sell in stores Friday and expects more deliveries.
Carphone Warehouse, a UK phone retailer, said interest for the latest iPhone is 10 times higher than for the first device. Neither company gave specific sales figures.
T-Mobile, owned by Deutsche Telekom, said it has received orders for several thousand iPhones in Germany alone, where the cheapest iPhone will sell for 1 euro. It also plans to offer it in the Netherlands and Austria starting on Friday.