How does an SMS work ?
How do SMS messages get sent to your phone ?
Even though now in use; your cell phone is constantly communicating information with nearby cell phone towers over a pathway called a control channel. This 'chatter' ensures that the cell phone system knows which 'cell' your phone is in as you move around.
Every so often, your phone and the tower will exchange a packet of data that lets them know that they are connected. Your phone also uses this control channel for call setup. When someone tries to call you; the tower sends your phone a message over the control channel that tells your phone to play its ringtone, and provides your phone with a pair of voice channel frequencies to use for the call. This control channel also provides the pathway for SMS messages. When you send or are sent a message; the message flows through the SMSC to the tower and forwards the message as a little packet of data on the control channel. The actual data format of the message includes the length of the message, a time stamp, the destination phone number and the format.
Advantages of SMS
SMS has several advantages. It is more discreet than a phone conversation, it is often less time-consuming to send a text message than to make a phone call or send an email, and is also convenient for deaf and hearing impaired people.
SMS is a store and forward service, meaning that any text message that you send, is sent to a central server (SMSC), which waits for the recipients phone to be active and in range of a cell phone tower before being delivered. The message will remain stored on the recipients SIM card unless deleted . SMS' can also be used to send a message to a large number of people at the same time. This service is called broadcasting and is used by companies to contact groups of employees or by online services to distribute news and other
information to subscribers. SMS are smaller packets and don’t overload the networks as much as phone calls.