PayPal’s interest in a cell phone service has been anticipated by industry watchers, as the U.S. wireless industry tests the idea of one day turning the cell phone into an “m-wallet” to replace cash, credit cards, and even apartment keys.

While U.S. consumers and wireless operators have been eyeing the m-wallet and pilot-testing various systems, Japanese wireless operators like NTT DoCoMo have already run successful services that use the phone for a credit card, ATM card, apartment key, and train ticket.