In San Francisco and don’t have change for a parking meter? Fear not. You can now pay for it using your cellphone.

The San Francisco Municipal Transportation Agency (SFMTA) has launched the PayByPhone parking payment service. Drivers can pull into a spot and pay for parking time online via a mobile device or call a toll-free number. The service is now available for parking meters in San Francisco’s Castro neighborhood and will spread to other areas of the city by early 2012.

“Parking is one of the greatest frustrations people experience in their daily lives,” said San Francisco District 8 Supervisor Scott Wiener, in a statement. “We need to make it easy to pay for parking, and this program puts us on that path. I’m thrilled that the Castro was chosen to roll out this innovative program.”

To use the system, drivers will enter the meter location number and the length of time they want to pay for on the phone. In addition, as time runs down on the parking meter, those using PayByPhone via cellphone will receive a text message reminder when time is about to expire, along with the ability to pay for additional time and receive receipts via email.

Parking spots are a part of the PayByPhone program will have a PayByPhone decal. Users of PayByPhone will be charged 45-cent fee each time they pay for parking with the technology.

“We look forward to providing additional convenience for our parking customers,” added Tom Nolan, chairman of the SFMTA board of directors. “Anything we can do to make it easier for folks to pay at the meter furthers our goal of helping our customers get to their destinations quickly and easily.”

Those drivers who have near field communication (NFC) on their mobile devices can physically “tap” the meter to access a streamlined payment process. Once PayByPhone is installed throughout all 30,800 SFMTA and 1,000 Port of San Francisco car and motorcycle parking meter spaces, the city believes it will be the largest NFC deployment in the United States.

Paying for parking via cell phone is becoming more common in big cities. In one example, Seattle will debut its own real-time “pay by cellphone” program in 2012. Seattle’s app will also charge users an additional 25- to 35-cent convenience fee to park, but the city hasn’t decided if the city or the citizen will pay those fees.