Apple Inc. redesigned the fourth generation of its smart phone, replacing sloping edges with a stainless steel band that wraps around the more squared-off sides. The metal band acts like a sturdy skeleton for the delicate phone, and it does double duty as the device’s antenna, reports the Associated Press. The iPhone 4 went on sale last Thursday morning in the U.S., the U.K., France, Germany and Japan. Within hours, some early buyers posted messages on Apple’s customer support website, complaining that gripping the gadget in ways that covered small black lines in the steel band could cause the number of “bars”–the indicator of call signal strength–to plummet. Some people said the iPhone 4 would disconnect mid-call when the phone was nestled in their hands in such a way that the lower-left corner of the device was covered.