Apple has said that any phone will lose signal strength when gripped in certain ways. It said the iPhone 4 seems to show a larger drop because it has been using a faulty formula to decide how many signal bars to show.
But Consumer Reports says it tested several phones that use AT&T Inc.'s network, and only the iPhone 4 seemed to have the reception issue.
Consumer Reports says the iPhone 4 will not be marked "recommended" on its updated smart phone ratings list because of this problem.