How Short Message Service (SMS) works - Amazon Pinpoint SMS

How Short Message Service (SMS) works

Short Message Service, commonly known as SMS, is a service that allows the exchange of text messages between mobile devices. SMS messages are typically short, with a maximum length of 160 characters, supported by virtually all mobile devices, and can be sent and received on various mobile networks. SMS is widely used for personal and business communication, providing a quick and convenient way to send concise messages to individuals or groups of people.

How does application to person (A2P) SMS work?

SMS uses the infrastructure that's already in place for voice calls, operating on the signaling channels of mobile networks. Here's a simplified overview of how SMS works:

  1. Application initiates a message. The application creates a text message and addresses the message to the recipient's phone number.

  2. Message is sent to the SMSC. The sender's application sends the message to the Short Message Service Center (SMSC), which is a centralized server responsible for handling SMS messages.

  3. SMSC determines the message route. By checking the recipient's phone number, the SMSC determines the appropriate network to deliver the message.

  4. SMSC delivers the message. The SMSC uses a series of signaling messages to send the message to the recipient's mobile network.

  5. Message is stored. The recipient's SMSC receives the message and temporarily stores it until the recipient's device is available to receive it.

  6. Recipient's device gets notified. When the recipient's device is reachable, the recipient's SMSC sends a notification message indicating that a new SMS is available.

  7. Message is retrieved: The recipient's mobile device connects to the recipient's SMSC to retrieve the message.

  8. Message displays: The recipient's mobile device receives the message and displays it to the recipient.

  9. Possible delivery confirmation. The recipient's mobile device may send a delivery receipt (DLR) confirmation back to the sender's SMSC, indicating that the message was successfully received.