US Patent 7835955 Time and/or attendance system using synchronized code

A time and/or attendance system is provided which includes a service location. The service location has a server with a first periodically changing random code that is correlated with actual time. A device displaying a second periodically changing random code is located at a selected location. The second periodically changing random code has the same sequence as the first periodically changing random code but the code being displayed on the device is offset in time from the first periodically changing random code. An employee who is expected to provide services at the selected location notes the second periodically changing random code at the beginning of an event at the selected location. Thereafter, the employee notes the second periodically changing random code at the end of the event at the selected location. After leaving the selected location, the employee communicates both the beginning code and the ending code to the service location. The communicated code is decoded at the service location to determine the times corresponding to the beginning code and the ending code, and such times are logged.