The mass transit system in Bucharest, Romania, will offer riders mobile ticketing beginning this month. The announcement from Metrorex, the system's operator, follows a successful pilot of the program at seven stations throughout the city.

Subscribers to wireless carriers Orange and Vodafone can send a text message to a special number that charges the customer's account and sends back a confirmation message. The rider then calls the same number and holds the handset near a special device at a station's entrance. Beeping generated by the phone is "heard" by the device, validating the purchase and allowing access to the platform.

According to Metrorex, the system reliably processed more than 10,000 validations during the pilot.  

The Bucharest metro network has 51 stations and transports more than 170 million passengers a year, Metrorex said.

Read more about contactless payments.