Car Alarm Key Fob - A key fob contains the functions of a remote keyless entry system, or are these functions are sometimes built into the ignition key handle itself. Buttons are dedicated to locking/unlocking the doors and opening the trunk, or, on station wagons and sport utility vehicles, unlocking and opening the rear tailgate. Some car alarm key fobs will also close any open windows, sunroof and roof when it remotely locks the car. Some remote keyless fobs for car alarms also feature a red panic button which activates the car alarm as a standard feature. A key fob is normally decorative and sometimes a useful item many people will often carry with their keys, on a ring or a chain. The key fob is often used for ease of tactile identification, to provide a better grip, or to make a personal statement. Key fobs are often called key rings or key chains in colloquial usage. Electronic key fobs are used for remote keyless entry systems on cars. Early electric key fobs were often operated by using infrared and they also required a clear line of sight to function. These remotes could easily be copied using a programmable remote control. More recent models use challenge-response authentication over a radio frequency. These key fob remotes are harder to copy and do not need to be in sight of the car to operate. The automotive dealership has to connect a diagnostic tool to program these remotes, but many of them can be self-programmed by following a sequence of steps in the car alarm manual and usually requires at least one working key. Two types of car pager alarms reviewed are the radio controlled key fob and the SMS text message that is sent to your mobile phone. Car pager alarms are designed to let you know if your car has been broken into or stolen even if you are too far away to hear the siren. for short, a radio pager will transmit a warning radio signal to a key fob and an SMS pager alarm will send you a text message on your mobile phone.