via rhodg (link):
“In this room, which is impervious to outside radio signals, our test engineers connected the phones to our base-station emulator, a device that simulates carrier cell towers,” the nonprofit organization wrote. “We also tested several other AT&T phones the same way, including the iPhone 3GS and the Palm Pre. None of those phones had the signal-loss problems of the iPhone 4.”
It continued: “Our findings call into question the recent claim by Apple that the iPhone 4’s signal-strength issues were largely an optical illusion caused by faulty software that ‘mistakenly displays 2 more bars than it should for a given signal strength.’ The tests also indicate that AT&T’s network might not be the primary suspect in the iPhone 4’s much-reported signal woes.”