 Keypads are similar to the pads that are used in telephone for
dialing numbers. The advantage of such a system is that the user does not have to
physically carry a card but has to just remember the password. So, unlike card based
system where if the card is lost the 'new' card holder can enter with the help of the lost
card, the keypad based system does not rely on physical cards and hence is not prone to
losses. This is a reliable and inexpensive method involving hardly any wear and tear.
While installing such a system care should be taken that when an authorized person is
entering his password then people standing around should not be able to view the punching
of numbers. In some systems special number entry guard is provided that makes it
impossible for any one to judge as to what number is being entered.
The better systems also have built-in mechanism to sound an alarm if the door remains open
for longer than set duration or allows the door to be opened within a specified duration.
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