Continental is the first airline in the U.S. to test the use of cell phones or PDAs as boarding passes with a pilot program at Bush Intercontinental Airport in Houston. Rather than being issued paper passes, passengers will receive a two-dimensional digital bar code on their phones. The code will be scanned and passengers will still need to show valid photo ID. If a passenger’s phone loses power, they can be issued a back-up paper pass. If the pilot is successful, the use of cell phones as boarding passes could extend to other airports and airlines.