Short Message Service (SMS)


SMS (Short Message Service) is a service for sending messages of up to 160 characters (224 characters if using a 5-bit mode) to mobile phones that use Global System for Mobile (GSM) communication. GSM and SMS service is primarily available in Europe. 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 a number of days until the phone is active and within range. SMS messages are transmitted within the same cell or to anyone with roaming service capability. They can also be sent to digital phones from a Web site equipped with PC Link or from one digital phone to another. Typical uses of SMS include:

An SMS gateway is a Web site that lets you enter an SMS message to someone within the cell served by that gateway or that acts as an international gateway for users with roaming capability.


The Short Message Service (SMS), as defined within the GSM digital mobile phone standard that is popular in Europe, the Middle East, Asia, Africa and some parts of North America, has several unique features.

A single SMS can be up to 160 characters of text in length. Those 160 characters can comprise of words or numbers or an alphanumeric combination. Non-text based SMS' (for example, in binary format) are also supported.

SMS is a store and forward service, in other words, SMS' are not sent directly from sender to recipient, but always via an SMS Center instead. Each mobile telephone network that supports SMS has one or more messaging centers to handle and manage the short messages.

SMS features confirmation of message delivery. This means that unlike paging, users do not simply send an SMS and trust and hope that it gets delivered. Instead the sender of the short message can receive a return message back notifying them whether the SMS has been delivered or not.

SMS' can be sent and received simultaneously with GSM voice, Data and Fax calls. This is possible because whereas voice, Data and Fax calls take over a dedicated radio channel for the duration of the call, short messages travel over and above the radio channel using the signaling path. As such, users of SMS rarely if ever get a busy or engaged signal as they can do during peak network usage times.

Ways of sending multiple SMS' are available. SMS concatenation (stringing several short messages together) and SMS compression (getting more than 160 characters of information within a single short message) have been defined and incorporated in the GSM SMS standards.