One person with direct knowledge of the phones design said Thursday that the iPhone 4 exposed a longstanding weakness in the basic communications software inside Apples phones and that the reception problems were not caused by an isolated hardware flaw.
Instead, the problems emerged in the complex interaction between specialized communications software and the antenna, said the person, who agreed to speak on the condition of anonymity because he was not authorized to discuss the matter.
The person said the problems were longstanding but had been exposed by the design of the iPhone 4. All cellphones can be affected by the way a hand grips the phone, but well-designed communications software compensates for a variety of external factors and prevents calls from dropping, the person said.
Mr. Jobs did not learn about the software problem until after the iPhone 4 shipped last month, the person said.
The glitch could presumably be fixed with a software update, and it appears to be unrelated to one that affected the display of the phones signal strength.