A service for sending short text messages using the Global System for Mobile Communications (GSM) cellular telephone system. Short Message Service (SMS) can send short messages of up to 160 alphanumeric characters.
SMS works as a store-and-forward service in which messages that are sent are stored at an SMS messaging center until the recipient can connect and receive them. SMS offers an advantage over paging systems in that it notifies the sender when the recipient has received the message. SMS allows messages to be sent or received simultaneously with voice, fax, or data transmission over GSM systems because it uses a separate signaling path instead of a dedicated channel. SMS thus works reliably even during peak usage periods of cellular systems.
Some SMS systems support compression to increase the amount of information that can be included in a message. You can also concatenate messages to create one message from several message fragments.
To use SMS, the user needs a subscription to a GSM bearer that supports SMS and a cell phone that supports SMS. The SMS function must be enabled for that user. (A subscription charge usually covers this.) SMS services are most widely deployed in Europe; more than 1 billion messages per month were sent in 1999.