Paging may seem like magic, but it's really
very simple. Here is how it works:

Steps to Page a Numeric Pager:
1- A caller dials a pager phone number. They're actually dialing into the paging terminal. The call reaches the paging terminal over telephone company lines in much the same manner as when you call a friend across town.

2- The tone a caller hears after dialing the pager number is the paging terminal telling the caller that it is ready to accept the page. After the message is entered, the terminal is signaled to send the message to 
the pager. The most common input devices for sending a page are the telephone keypad (for numeric messages) and keyboard entry devices such as a computer or connection to a dispatch service (for text messages).

3- The paging terminal is linked to numerous transmitters through the paging coverage area. When it receives a message (for a specific pager), the terminal converts the message into a pager code and relays this code to the transmitters. The transmitters send out the code (as a radio signal) throughout the entire coverage area.

4- The code is picked up by all of the pagers within the coverage area on that particular frequency, but only the pager with the proper code is alerted and will display the message.

Steps to Page an Alphanumeric:
1- The page's journey begins when someone enters a page for you, usually calling by telephone. Your page is then converted into a digital data stream traveling over phone lines to a public switched telephone network (PSTN) where it is rerouted onto the paging terminal. 

2- At the paging terminal, the data stream is "back-hauled" to the 
central uplink teleport.

3- Once the data stream reaches the teleport, or earth station, it is processed by modulation equipment in preparation for the trip to space. From the modulator, the data is sent into space through a large satellite dish aimed at a particular paging satellite. 

4- Over 22,000 miles above the Earth, the signal makes a U-turn at the satellite transponder. The transponder receives the signal, amplifies it, then retransmits it back down to earth at the speed of light. 

5- Back on earth, the signal is received by hundreds of satellite receiver dishes located near the paging transmitters. The data stream travels from the receiver dish via cable to a digital data receiver. From the receiver, the signal is sent to the paging transmit controller which prepares it to be sent to your pager. 

6- From the transmit controller, the signal is broadcast via radio waves to your pager.