Short Message Service (SMS)

What is SMS (Short Message Service)?

SMS (Short Message Service), commonly referred to as "text messaging," is a service for sending short messages of up to 160 characters (224 character limit if using a 5-bit mode) to mobile devices, including cellular phones and smartphones.

How does SMS work?

SMS is similar to paging. However, SMS messages do not require the mobile phone to be active and within range and will be held for several days until the phone is active and within range.

SMS messages are transmitted via mobile data over cellular networks -- starting with 2G -- to anyone with roaming service capability.

They can also be sent digitally in many other ways, including the following:

• from one Wi-Fi-enabled device to another;
• from web-based applications within a web browser;
• from instant messaging clients;
• from VoIP applications like Skype; and
• from some unified communications applications.

What are the use cases for SMS?

Typical use cases of SMS include the following:

• sending notifications from service centers to a customer;
• sending a notification of delivery by e-commerce platforms;
• sending a notification to a mobile phone owner of a voicemail message;
• sending promotional messages to cell phones as part of SMS marketing;
• sending a notification to subscribers about their plans; and
• sending codes as part of a multifactor authentication platform.

The growth of SMS text messages also led to the development of an Enhanced Messaging Service (EMS) and Multimedia Messaging Service (MMS).

EMS is an adaptation of SMS that allows users to send and receive ringtones and operator logos, as well as combinations of simple media to and from EMS-compliant handsets.

Further, MMS allows multimedia files to be shared over a cellular network, including pictures and videos.

Many of these depend upon short phone numbers called common short codes (CSCs), usually consisting of five digits, used to address SMS and MMS messages from cellular telephones.

Further, users can send messages from a computer via an SMS gateway. SMS gateways allow users to send messages to people within the cell served by that gateway. They also serve as international gateways for users with roaming capability.

Challenges with SMS

In recent years, SMS spam has become an issue, as has SMiShing, a security attack in which the user is tricked into downloading a Trojan horse, virus or other malware onto a cellular phone or another mobile device.

Additionally, the growth of social media platforms used as communication channels has outpaced the use of telecommunication-based SMS services.

This has changed the nature of text messaging services. Instead of relying on SMS technology, users commonly text each other using social media apps such as WhatsApp or Facebook Messenger.

See also: SMS spam, short message service center, A2P messaging, call tree and two-factor authentication.