A ringing cell phone can be a nuisance to others in some places like a theatre or at important meetings. A pager is very useful then, because it 
alerts you that someone is trying to contact you by vibrating silently. How does a pager work? If you want to page your friend, you must first dial the number of his paging service provider. You will then be connected to a computerized terminal which instructs you to key in your telephone number, and then press the ‘star’ key on your phone to complete the message. The paging terminal routes the signal to a radio transmitter. If your friend’s pager is switched on, and within the radio transmitters range, it will recognize the coded signal sent by the radio transmitter. The pager then converts the signal into data, and alerts your friend with a beep or vibration. You number will be displayed on his pager, and he can then call you back whenever it is convenient to him.
