The owner of the property needed to know whether the system was armed or disarmed before opening the door. Lights were used to indicate whether the system was on or off. A lot of effort was spent to find a way to let the owner get into a protected property without announcing to anyone outside whether the system was armed or disarmed. The solution to the outside keystation was to program an entry delay for certain detection devices that allowed the customer time to disarm an alarm system from inside the protected area. These newer systems require a code be entered in a keypad after entering the premises.
Some systems use wireless keys or wireless keypads to disarm the alarm system.
These devices may be the only wireless devices on a traditional wired alarm system, or they may be just part of a complete wireless alarm system. More can be read on this topic by following this link to a document on enhanced security. Wireless keypads do not require immediate service if they are lost or stolen. Though service would be required to replace or remove the lost wireless keypad, there is no need to race to the system. Knowing the proper code would still be required to disarm a system using a wireless keypad.