News.com is reporting that Motorola is working with T-Mobile and Cingular to replace defective shipped last month. A faulty component in the slim, popular phones is causing them to randomly drop calls and reboot. The two carriers, which stopped selling Razrs earlier this week, told News.com that customers with affected handsets may bring them to carrier stores for an exchange. Motorola spokesman Alan Buddendeck said Razrs without the glitch will be available by next week. Verizon's Razr V3c was not affected.