There are some uses for the phoning home practice that are legal in some countries. For example, phoning home could be for purposes of access restriction, such as transmitting an authorization key. This is done with the Adobe Creative Suite. Each time one of the programs is opened, it phones home with the serial number. If the serial number is listed as being already in use, or a fake, then the program will present the user with the option of inputting the correct serial number. If the user refuses, the next time the program loads, it will operate in trial mode until a valid serial number has been input. However, the method can be thwarted by either disabling the internet connection when starting the program or adding a firewall or Hosts file rule to prevent the program from communicating with the verification server.