Apple is to update its latest iPhone only weeks after it went on sale, after it admitted there was a problem with how the phone calculates signal strength.
Users had complained that gripping the phone at a certain point caused it reduce or lose signal completely.
In a statement today, Apple promised a software fix within weeks for the flaw, which misrepresents the strength of signal the phone is receiving. The error also affects the previous 3G and 3GS models.
"Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays two more bars than it should for a given signal strength," it said.
The company again defended the iPhone 4 against the claims that gripping it in a certain position would affect reception.
"Gripping almost any mobile phone in certain ways will reduce its reception by one or more bars. This is true of iPhone 4, iPhone 3GS, as well as many Droid, Nokia and RIM phones,"the statement said.
"But some users have reported that iPhone 4 can drop 4 or 5 bars when tightly held in a way which covers the black strip in the lower left corner of the metal band. This is a far bigger drop than normal, and as a result some have accused the iPhone 4 of having a faulty antenna design."
Apple said the fault was not with the design but with the software.
"Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don't know it because we are erroneously displaying four or five bars. Their big drop in bars is because their high bars were never real in the first place."
The new software fix, promised within weeks, would make this more accurate, the company said.
The iPhone was unveiled by Apple's chief executive Steve Jobs on June 7th. It went on sale in five countries, including the US and the UK, on June 24th. It will not be available in Ireland until the end of July.
Introduced in 2007, the iPhone is now Apple’s top-selling product, with more than 50 million of the devices sold. The iPhone 4 has already sold more than 1.7 million units since its launch.
