Phoning Home - Legal Phoning Home

Legal Phoning Home

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.

Phoning home could also be for marketing purposes, such as the "Sony BMG Rootkit", which transmits a hash of the currently playing CD back to Sony, or a digital video recorder (DVR) reporting on viewing habits. High-end computing systems such as mainframes have had 'phone home' capabilities for many years, to alert the manufacturer of hardware problems with the mainframes or disk storage subsystems (this enables repair or maintenance to be performed quickly and even proactively under the maintenance contract). Similarly, high-volume copy machines have long been equipped with phone-home capabilities, both for billing and for preventive/predictive-maintenance purposes.

Aside from malicious software phoning home, phoning home may be done to track computer assets—especially mobile computers. One of the most well-known software applications that leverages phoning home for tracking is Absolute Software's CompuTrace. This software employs an agent which calls into an Absolute-managed server on regular intervals with information companies or the police can use to locate a missing computer.