SAN FRANCISCO - For many people yesterday, the iPhone was the iCan't.
Apple suffered widespread network gridlock yesterday morning, as many of the 6 million users of the original iPhone tried to upgrade to new software while the first buyers of the new iPhone 3G were trying to activate their purchases.
The meltdown was a classic example of problems that can result when complex systems have single points of failure. In this case, the company appeared almost to invite the problems by having both existing and new iPhone owners try to get through to its systems at the same time.
"There are certainly lessons in preparedness," said Richard Doherty, a consumer electronics industry consultant who is president of the Envisioneering Group in Seaford, N.Y.
The problems led to slow-moving lines of would-be iPhone 3G purchasers at Apple and AT&T; stores, while current iPhone users found that their phones stopped working when they tried to upgrade them to the latest software. The iPhone must connect to Apple servers through the iTunes program for authentication before it will function again after a software upgrade.
Apple did not comment publicly on the problems, but executives privately acknowledged them and said the combination of the software upgrades and new iPhone 3G owners trying to complete their activation had swamped the company's servers.
At Apple and AT&T; stores yesterday morning, employees began instructing purchasers to take their new iPhones home and activate them there. However, the iTunes servers were equally hard to reach from home.
A year ago, when the original iPhone went on sale, customers performed the activation process at home. But Apple and its cell phone partners changed the process this time, in part because the carriers are partially subsidizing the cost of the phones, so they are eager to make sure that phone buyers are locked into a contract.
Many of the original iPhones were bought in the United States and then taken overseas for use on foreign carriers. Some industry executives have said that the change in policy was intended to reduce the number of phones that were bought and then modified for use on unauthorized cellular networks.
Mark Siegel, a spokesman for AT&T;, Apple's cellular partner in the United States, said the rush of customers and upgrades had overwhelmed Apple's servers. "Apparently the iTunes system has just been overwhelmed by demand and Apple is working very hard to get this fixed," he said.
The Associated Press contributed to this article.