Short Messaging Service (SMS)

Short Message Service (SMS) is the ability to send and receive short alphanumeric messages to and from mobile telephones. SMS can also be used as a transport for binary payloads and to implement the WAP stack on top of the SMSC bear. SMS was created as part of the GSM Phase 1 standard. SMS allows users to directly transmit messages to each other without the use of an operator (it is, however, necessary to have the underlying operator controlled wireless service). The first user can send a message to a mobile unit, via a direct connect computer. The SMS protocol of messaging is also "smarter" then standard paging. SMS is a store and forward method therefore, if the end user is not available, the mobile unit is powered off, or the unit is outside a service area, when the unit comes back on line the message will appear. A SMS message can also be sent "certified," where it will notify the message originator of the end user's receipt of the message.
SMS appeared on the wireless scene in 1991 in Europe. The European standard for digital wireless, now known as the Global System for Mobile Communications (GSM), included short messaging services from the outset. In North America, SMS was made available initially on digital wireless networks built by early pioneers such as BellSouth Mobility, PrimeCo, and Nextel, among others. These digital wireless networks are based on GSM, code division multiple access (CDMA), and time division multiple access (TDMA) standards.
Network consolidation from mergers and acquisitions has resulted in large wireless networks having nationwide or international coverage and sometimes supporting more than one wireless technology. This new class of service providers demands network-grade products that can easily provide a uniform solution, enable ease of operation and administration, and accommodate existing subscriber capacity, message throughput, future growth, and services reliably. Short messaging service center (SMSC) solutions based on an intelligent network (IN) approach are well suited to satisfy these requirements, while adding all the benefits of IN implementations.

Enhanced Messaging Service (EMS ) is basically is an extension of Short Message Service, which enables the ringtones, wappush, mms notifications, SIM toolkit applications etc binary oriented messaging.

SMS References:

Messaging- SMS, SMPP, MMS Discussion Forum

HSS World SMS FAQ

MessagingBlog

SMS/EMS/MMS tutorials

What is SMS?

Sun SMS Overview

Sun Wireless Messagin API

SMS Vulnerability Analysis

India Bulk SMS