Free parking - ParkMobile parking app glitch

You can park for free seemingly wherever ParkMobile is installed thanks to a glitch. I tried this in Atlanta and in Washington, DC. All you have to do is use a test credit card number. These numbers are designed for testing payment systems. I used the test Visa card 4111111111111111 (you can use any expiration date in the future). Here is a test credit card list: https://www.paypalobjects.com/en_US/vhelp/paypalmanager_help/credit_card_numbers.htm Here is a picture of a sign in Washington DC if you want to try it out: http://www.flickr.com/photos/daquellamanera/5959309079/ (these signs are on all the meters in DC) Free parking baby!