The launch of Apple's much-anticipated new iPhone turned into an information-technology meltdown, as customers were unable to get their phones working, an Associated Press report said.
Some customer even reported spending two hours on the phone with Apple and AT&T, trying to get the new iPhones to work, the report said.
In stores in the US, people waited at counters to get the phones activated, as lines built behind them.
Many of the customers had already camped out for several hours in line to become among the first with the new phone, which updates the one launched a year ago by speeding up internet access and adding a navigation chip.
A spokesman for AT&T, the exclusive carrier for the iPhone in the US, said there was a global problem with Apple's iTunes servers that prevented the phones from being fully activated in-store, as had been planned, the Associated Press report further said.
Instead, employees are telling buyers to go home and perform the last step by connecting their phones to their own computers, spokesman Michael Coe said.
However, the iTunes servers were equally hard to reach from home, leaving the phones unusable except for emergency calls.
The problem extended to owners of the previous iPhone model. A software update released for that phone on Friday morning required the phone to be reactivated through iTunes.
When the first iPhone went on sale a year ago, customers performed the whole activation procedure at home, freeing store employees to focus on sales. But the new model is subsidized by carriers, and Apple and AT&T therefore planned to activate all phones in-store to get customers on a contract.
The new phone went on sale in 21 countries on Friday, creating a global burden on the iTunes servers.