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SMS Introduction

The Short Message Service (SMS) allows text messages to be sent and received to and from mobile telephones. The text can comprise words or numbers or an alphanumeric combination. SMS was created as part of the GSM Phase 1 standard. The first short message is believed to have been sent in December 1992 from a PC to a mobile phone on the Vodafone GSM network in the UK. Each short message is up to 160 characters in length when Latin alphabets are used, and 70 characters in length when non-Latin alphabets such as Arabic and Chinese are used.

There is no doubting the success of SMS. The market in Europe alone had reached over three billion short messages per month as of December 1999, despite little in proactive marketing by network operators and phone manufacturers. Key market drivers over the next two years, such as the Wireless Application Protocol (WAP), will continue this growth path.

Typical uses of SMS include notifying a mobile phone owner of a voicemail message, alerting a salesperson of an inquiry and telling a driver the address of the next pickup.


SMS is essentially similar to paging, but SMS messages do not require the mobile phone to be active and within range, as they 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 capability. They can also be sent to digital phones from a web site equipped with a PC Link or from one digital phone to another. An SMS gateway is a web site that lets you enter an SMS message to someone within the cell served by that gateway or acts as an international gateway for users with roaming capability.

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

The SMS features confirmation of message delivery. This means that, unlike paging, users do not simply send a short message 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 short message has been delivered or not.

Short messages can be sent and received simultaneously with GSM (Global System for Mobile Communications) 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 short messages 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.

The network operator needs to purchase its first generation SMS Center as part of the network commissioning plan. The initial SMS Center may simply be a voice mail platform module or a stand-alone SMS Center. It is not possible to make the SMS available without an SMS Center since all short messages pass through the SMS Center.


Because simple person-to-person messaging is such an important component of total SMS traffic volumes, anything that simplifies message generation is an important enabler of SMS. Predictive text input algorithms significantly reduce the number of key strokes that need to be made to input a message. T9, from Tegic, anticipates which word the user is trying to generate. Widespread incorporation of such algorithms into the installed base of mobile phones will typically lead to an average uplift in SMS traffic of 25% per enabled user. These predictive text algorithms support multiple languages.

The introduction of standardised protocols such as SIM Application Toolkit and the Wireless Application Protocol (WAP) contribute to an increase in messaging usage by providing a standard service development and deployment environment for application developers and business partners. These protocols also make it easier for users to reply to and otherwise access messaging services through custom menus on the phone. While these protocols are only a means to an end and not new messaging destinations or services, they are likely to lead to a 10-15% uplift in total SMS volumes.

The introduction of more user-friendly terminals contributes to increases in messaging usage. Terminals such as smart phones make it easier for users to originate, reply to and otherwise access messaging services through the provision of a QWERTY keyboard, rather than the limited keypad on standard mobile phones.