SMS is a means to send text-based messages to mobile devices. Mobile users can send and receive messages through this service. SMS messaging requires a service center called an SMS Center (SMSC) that handles, stores, and forwards the millions of messages each day. Its phenomenal growth is mainly attributed to the growth of youth culture in developed countries, mobile phone ownership, ease of use, addition of email and other information services, price and the Mobile Originate service.

This service is nowadays available in almost all the wireless networks such as Global Mobile Communications (GSM) networks, Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA) etc.

SMS travels over a separate signaling channel, called out-of-band signaling, to that of voice or data traffic. Out-of-band signaling establishes a digital channel, called a signaling link, for the exchange of signaling information, which has enough space to accommodate SMS messaging. To work on a physical level, SMS messaging is dependent on a couple of basic entities such as short message entity (SME) that originates or receives the message and SMC Center that receives, stores and forwards messages. An SME can be any SMS-enabled communication device.

When transmitting to or from a SMS-enabled device, the message has to pass through the Mobile Switching Center (MSC). Once into the mobile network, the message will be routed using an enhancement to the signaling system (SS7) called the Mobile Application Part (MAP). If a message can not be delivered, the SMSC will store the message to be delivered later.For a stipulated time period, the message will be forwarded repeatedly to the intended recipient. If still unsuccessful, the sender will be notified that the particular message could not be delivered.

SMS has several unique features as mentioned below. SMS messaging uses the signaling layer, part of the communication channel, so it can not support large amounts of data. Since SMS is currently used predominantly for text-based messages, this works well without any obvious hindrance other than from message length.

1. An SMS message content can be words of characters, numbers, or a combination of both and basic pictures or icons can also be attached in it. But the total length can be up to 160 characters.
2. SMS has store and forward feature also and thus the mobile communication is not between two users but each message has to be routed through an intermediate referred to as SMSC.
3. When an SMS message is sent to one or more receivers, an acknowledgement is guaranteed.
4. Since SMS uses a separate signaling path rather than a dedicated radio channel, messages can be sent simultaneously with voice, data and fax and thus users can send messages during peak hours also without any interruptions
5. The telephone number of the sender of the message is automatically attached with the message itself and thereby facilitates the receiver to know who the sender is and to send a reply.
6. SMS provides means to concatenate several short messages together and compress more than  160 characters of data within a single short message. That is, SMS helps to send multiple messages simultaneously.

There are other mobile data services. Still SMS maintains its own distinct advantages for various user categories. SMS brings some unique advantages over other similar data communication services.

SMS provides a two-way messaging, allows for a higher degree of roaming and includes delivery confirmations. SMS offers store and forward capability and out-of-band signaling that provides a high guarantee for SMS message delivery. SMS messages can be sent and received through any communication channel without interruption from other types of communication. A corporate business users can benefit greatly as it facilitates to

1. take notes electronically and reference them later
2. send messages even when the phone is in use
3. deliver single message to multiple users
4. provides automatic delivery after recipients switch on their phones
5. notifies sender about message delivery
6. connects in poor reception areas where a voice call can not be established

Greater bandwidth-providing technologies such as 2.5-generation (2.5G) and 3-generation (3G) are set to activate new types of messaging in the years to come.It is expected that there are other innovative mobile applications such as pushing and pulling of informational content, Picture Messaging and Multimedia Messaging Service (MMS) that are to take the messaging to new heights in the days to come among the mobile users. Messaging can be done using different channels to support longer and more flexible sizes that allow different kinds of content to be transferred over the same service/bearer such as video clips and graphics and thus the popularity of messaging - whether text, picture or multimedia - will continue to go ahead.

SMS has many benefits for both the service providers and also to the users providing easy establishment of services, costing very less and facilitating users to write and send messages in an easy manner.