ExxonMobil Corp. has implemented a new driver-safety policy that bans employees from using cell phones while driving on company business, CNN reported. The new rule, posted on the company's internal Web site, says employees cannot use cell phones while driving and should allow incoming calls to be answered by voice mail. Employees should only retrieve messages and make calls once they have parked in a safe and secure location, the memo states. The company cited studies showing that accidents are four times more likely to happen when cell phones are used while driving compared with drivers not using cell phones, the news agency reported. ExxonMobil said its employees and contractors, collectively, drive up to 1.5 million miles each day.