Apple is expected to have a record iPhone 5 debut, but the high demand has raised questions about the company's supply capacity and whether it will be able to keep up with demand. Customers lined up for days in Sydney, Tokyo, Paris, and New York, anxiously waiting to pick up the latest model of Apple's top-selling iPhone.

Global sales started in Sydney at the Apple Store on George Street at 8 a.m. local time,with roughly 500 people lined up to buy the handset. The iPhone 5 also went on sale in Japan, Hong Kong, Singapore, Germany, France, the UK, Canada and the U.S. Customers can grab the new-generation iPhone with a new wireless contract for $199, $299 and $399 in the United States, depending on configuration.

Apple co-founder Steve Wosniak was also among the several hundred people waiting in line for the new iPhone in Brisbane, Australia.

"I just feel this impulse, like I want to be part of this big adventure, this big revolution and this advance in technology," he told local television. Wosniak departed from Apple in the late 1980s.

The crowds seem to confirm analysts' estimates that the iPhone 5 will make the largest consumer-electronics debut in history. According to Piper Jaffray analyst Gene Munster, Apple may sell a whopping 10 million iPhones during the weekend sales rush.

A successful debut is crucial to Apple's endeavors to fuel growth, as the iPhone accounts for roughly two thirds of the company's profit. Apple rose 0.2 percent to the equivalent of $701.54 as of 9.21 a.m. in Frankfurt trading. The Apple Store in Frankfurt's financial district had about 1,000 people gathered in line for the opening.

Apple is releasing the iPhone 5 globally faster than any of the previous five debuts of the popular device. According to Apple, the iPhone will go on sale in 22 more countries on Sept. 28, and in more than 100 countries by the end of the year. 

Japanese carrier KDDI said it had already run out of the new iPhone 5, while Australia's Telstra said online pre-orders sold out in a record 18 hours. Telstra is currently discussing accelerated restocking with Apple. As demand for the new iPhone keeps growing, so are concerns that Apple may face difficulties in keeping up with initial demand due to supply shortages of components such as in-cell displays, said Barclays Plc. The company is already forced to push some deliveries to October after early online purchases doubled the record set last year with the iPhone 4S, topping 2 million in just 24 hours.