How SMS works

SMS (Short Message Service) is a technology that allows users to send and receive text messages on their mobile devices. Here’s an explanation of how SMS works, including both Person-to-Person (P2P) and Application-to-Person (A2P) SMS messaging.

How SMS Works

1. Message Creation

2. Message Transmission

3. Message Routing

4. Message Delivery

5. Delivery Receipt

Key Components

  1. Mobile Device: The sender and recipient use mobile devices equipped with SMS functionality.
  2. Base Stations (Cell Towers): These are the intermediary points that facilitate communication between mobile devices and the network.
  3. Short Message Service Center (SMSC): The central component in the SMS network, responsible for storing and forwarding messages.
  4. Home Location Register (HLR): A database that keeps track of the locations and statuses of mobile devices within the network.

Network Architecture

  1. Mobile Originated (MO) SMS: The process where the SMS is sent from the mobile device to the network.
  2. Mobile Terminated (MT) SMS: The process where the SMS is delivered from the network to the mobile device.
  3. GSM/UMTS/LTE: SMS was initially developed for GSM (Global System for Mobile Communications) networks, but it is now supported across all major mobile network technologies, including UMTS (Universal Mobile Telecommunications Service) and LTE (Long Term Evolution).


P2P SMS (Person-to-Person)

A2P SMS (Application-to-Person)