While talking with an Orange mobile phone salesman in France, he mentioned one of the major problems they have experienced lately from regular customers and travelers is RFID protected bags and purses. People buy these RFID protected bags and purses to protect their chip & pin credit cards and passports from being scanned. When you stick your phone in one of these RFID protected bags or purses, you get no signal, your phone won't ring. Your phone is constantly searching for a signal and heats up and drains your battery. Here are some examples of RFID protected bags and purses:
Amazon.com: rfid bags: Clothing & Accessories
Amazon.com: rfid bags: Clothing & Accessories