Apple will issue a patch to fix a glitch in iPhone antenna software that causes it to misstate the network signal level.
In an open letter to iPhone owners Friday, Apple said it was “stunned” to discover the problem in its bar-calculation formula, which dates back to the original iPhone.
The dodgy code causes the device to display more signal bars than the users are actually receiving, Apple admitted, following weeks of complaints from iPhone 4 owners.
“Our formula, in many instances, mistakenly displays two more bars than it should for a given signal strength,” the firm states.
It said it would issue a free software update “within a few weeks” to all iPhone 3GS, 3G and iPhone 4 phones.
The patch will use an AT&T formula that Apple promises will give a more accurate reading of signal strength.
The firm also plans to make its second and third bars larger, to make them easier to read.
Web forums lit up with reports of reception problems within a few hours of the launch of the latest iPhone on June 24, and some disgruntled buyers have since initiated class-action lawsuits, claiming a breach of implied warranty.
Apple says it discovered the problem when investigating complaints from iPhone 4 users about the loss of signal when the bottom half of the phone is held tightly.
Apple said in its letter that “many Droid, Nokia and RIM phones” also lost network signal strength when held tightly, but conceded the loss of four or five bars on the iPhone 4 was “far bigger” than normal.
Rivals Motorola and Nokia have made the most of the Apple flaw, with Motorola poking fun at the problems in a newspaper ad, and Nokia issuing a “how to” guide on holding its phones.