Short Message Service ( SMS) is a text messaging service component of most telephone, World Wide Web, and mobile telephony systems. It uses standardized communication protocols to enable fixedline or mobile phone devices to exchange short text messages. SMS was the most widely used data application, with an estimated 3.5 billion active users, or about 80% of all mobile phone subscribers, at the end of 2010.
SMS, as used on modern handsets, originated from radio telegraphy in radio memo pagers that used standardized phone protocols. These were defined in 1985 as part of the Global System for Mobile Communications (GSM) series of standards.GSM Doc 28/85 "Services and Facilities to be provided in the GSM System" rev2, June 1985 The protocols allowed users to send and receive messages of up to 160 alpha-numeric characters to and from GSM mobile handsets. Though most SMS messages are mobile-to-mobile text messages, support for the service has expanded to include other mobile technologies, such as ANSI CDMA networks and Digital AMPS, as well as satellite and landline networks.
SMS is also employed in mobile marketing, a type of direct marketing. According to one market research report, as of 2014, the global SMS messaging business was estimated to be worth over $100 billion, accounting for almost 50 percent of all the revenue generated by mobile messaging.
The SMS concept was developed in the Franco-German GSM cooperation in 1984 by Friedhelm Hillebrand and Bernard Ghillebaert.See the book Hillebrand, Trosby, Holley, Harris: SMS the creation of Personal Global Text Messaging, Wiley 2010 The GSM is optimized for telephony, since this was identified as its main application. The key idea for SMS was to use this telephone-optimized system, and to transport messages on the signalling paths needed to control the telephone traffic during periods when no signalling traffic existed. In this way, unused resources in the system could be used to transport messages at minimal cost. However, it was necessary to limit the length of the messages to 128 bytes (later improved to 160 seven-bit characters) so that the messages could fit into the existing signalling formats. Based on his personal observations and on analysis of the typical lengths of postcard and Telex messages, Hillebrand argued that 160 characters was sufficient to express most messages succinctly.
SMS could be implemented in every mobile station by updating its software. Hence, a large base of SMS-capable terminals and networks existed when people began to use SMS.See GSM document 28/85rev.2 June 85 and GSM WP1 document 66/86 available in the ETSI archive A new network element required was a specialized short message service centre, and enhancements were required to the radio capacity and network transport infrastructure to accommodate growing SMS traffic.
The first proposal which initiated the development of SMS was made by a contribution of Germany and France into the GSM group meeting in February 1985 in Oslo.GSM document 19/85, available in the ETSI archive This proposal was further elaborated in GSM subgroup WP1 Services (Chairman Martine Alvernhe, France Telecom) based on a contribution from Germany. There were also initial discussions in the subgroup WP3 network aspects chaired by Jan Audestad (Telenor). The result was approved by the main GSM group in a June '85 document which was distributed to industry.GSM document 28/85r2, available in the ETSI archive The input documents on SMS had been prepared by Friedhelm Hillebrand (Deutsche Telekom) with contributions from Bernard Ghillebaert (France Télécom). The definition that Friedhelm Hillebrand and Bernard Ghillebaert brought into GSM called for the provision of a message transmission service of alphanumeric messages to mobile users "with acknowledgement capabilities". The last three words transformed SMS into something much more useful than the prevailing messaging paging that some in GSM might have had in mind.
SMS was considered in the main GSM group as a possible service for the new digital cellular system. In GSM document " Services and Facilities to be provided in the GSM System," both mobile-originated and mobile-terminated short messages appear on the table of GSM teleservices.
The discussions on the GSM services were concluded in the recommendation GSM 02.03 " TeleServices supported by a GSM PLMN." GSM TS 02.03, Teleservices Supported by a GSM Public Land Mobile Network (PLMN). Here a rudimentary description of the three services was given:
The material elaborated in GSM and its WP1 subgroup was handed over in Spring 1987 to a new GSM body called IDEG (the Implementation of Data and Telematic Services Experts Group), which had its kickoff in May 1987 under the chairmanship of Friedhelm Hillebrand (German Telecom). The technical standard known today was largely created by IDEG (later WP4) as the two recommendations GSM 03.40 (the two point-to-point services merged) and GSM 03.41 (cell broadcast).
WP4 created a Drafting Group Message Handling (DGMH), which was responsible for the specification of SMS. Finn Trosby of Telenor chaired the draft group through its first 3 years, in which the design of SMS was established. DGMH had five to eight participants, and Finn Trosby mentions as major contributors Kevin Holley, Eija Altonen, Didier Luizard and Alan Cox. The first action planDocument GSM IDEG 79/87r3, available in the ETSI archive mentions for the first time the Technical Specification 03.40 "Technical Realisation of the Short Message Service". Responsible editor was Finn Trosby. The first and very rudimentary draft of the technical specification was completed in November 1987.GSM 03.40, WP4 document 152/87, available in the ETSI archive However, drafts useful for the manufacturers followed at a later stage in the period. A comprehensive description of the work in this period is given in.Finn Trosby, "the strange duckling of GSM SMS", Telektronikk Vol.3 2004.
The work on the draft specification continued in the following few years, where Kevin Holley of Cellnet (now Telefónica O2 UK) played a leading role. Besides the completion of the main specification GSM 03.40, the detailed protocol specifications on the system interfaces also needed to be completed.
From 3GPP Releases 99 and 4 onwards, CAMEL Phase 3 introduced the ability for the Intelligent Network (IN) to control aspects of the Mobile Originated Short Message Service,CAMEL Phase 3 specification, available from the 3GPP web site. while CAMEL Phase 4, as part of 3GPP Release 5 and onwards, provides the IN with the ability to control the Mobile Terminated service.CAMEL Phase 4 specification, also available from the 3GPP specification page. CAMEL allows the gsmSCP to block the submission (MO) or delivery (MT) of Short Messages, route messages to destinations other than that specified by the user, and perform real-time billing for the use of the service. Prior to standardized CAMEL control of the Short Message Service, IN control relied on switch vendor specific extensions to the INAP of SS7.
The first commercial deployment of a short message service center (SMSC) was by Aldiscon part of Logica (now part of Acision) with Telia (now TeliaSonera) in Sweden in 1993, followed by Fleet Call (now Nextel) in the US, Telenor in Norway and BT Cellnet (now O2 UK) later in 1993. All first installations of SMS gateways were for network notifications sent to mobile phones, usually to inform of voice mail messages.
The first commercially sold SMS service was offered to consumers, as a person-to-person text messaging service by Radiolinja (now part of Elisa) in Finland in 1993. Most early GSM mobile phone handsets did not support the ability to send SMS text messages, and Nokia was the only handset manufacturer whose total GSM phone line in 1993 supported user-sending of SMS text messages. According to Matti Makkonen, the inventor of SMS text messages, Nokia 2010, which was released in January 1994, was the first mobile phone to support composing SMSes easily.
Initial growth was slow, with customers in 1995 sending on average only 0.4 messages per GSM customer per month. GSM World press release One factor in the slow takeup of SMS was that operators were slow to set up charging systems, especially for prepaid subscribers, and eliminate billing fraud which was possible by changing SMSC settings on individual handsets to use the SMSCs of other operators. Initially, networks in the UK only allowed customers to send messages to other users on the same network, limiting the usefulness of the service. This restriction was lifted in 1999.
Over time, this issue was eliminated by switch billing instead of billing at the SMSC and by new features within SMSCs to allow blocking of foreign mobile users sending messages through it. By the end of 2000, the average number of messages reached 35 per user per month, and on Christmas Day 2006, over 205 million messages were sent in the UK alone.
In 2014, Caktus Group developed the world's first SMS-based voter registration system in Libya. So far, more than 1.5 million people have registered using that system, providing Libyan voters with unprecedented access to the democratic process.
While SMS is still a growing market, traditional SMS is becoming increasingly challenged by alternative messaging services such as Facebook Messenger, WhatsApp and Viber available on smart phones with data connections, especially in Western countries where these services are growing in popularity. It has been reported that over 97% of smart phone owners use alternative messaging services at least once a day. Enterprise SMS-messaging, also known as application-to-peer messaging (A2P Messaging) or 2-way SMS, continue to grow steadily at a rate of 4% annually. Enterprise SMS applications are primarily focused on CRM and delivering highly targeted service messages such as parcel-delivery alerts, real-time notification of credit/debit card purchase confirmations to protect against fraud, and appointment confirmations. Another primary source of growing A2P message volumes is two-step verification (alternatively referred to as 2-factor authentication) processes whereby users are delivered a one-time passcode over SMS and then are asked to enter that passcode online in order to verify their identity.
Messages are sent to a short message service center (SMSC), which provides a "store and forward" mechanism. It attempts to send messages to the SMSC's recipients. If a recipient is not reachable, the SMSC queues the message for later retry.Gil Held: "Data over Wireless Networks." pages 105–11, 137–38. Wiley, 2001. Some SMSCs also provide a "forward and forget" option where transmission is tried only once. Both mobile terminated (MT, for messages sent to a mobile handset) and mobile originating (MO, for those sent from the mobile handset) operations are supported. Message delivery is "best effort," /ref> Some providers allow users to request delivery reports, either via the SMS settings of most modern phones, or by prefixing each message with *0# or *N#. However, the exact meaning of confirmations varies from reaching the network, to being queued for sending, to being sent, to receiving a confirmation of receipt from the target device, and users are often not informed of the specific type of success being reported.
SMS is a stateless communication protocol in which every SMS message is considered entirely independent of other messages. Enterprise applications using SMS as a communication channel for stateful dialogue (where an MO reply message is paired to a specific MT message) requires that session management be maintained external to the protocol.
Larger content (concatenated SMS, multipart or segmented SMS, or "long SMS") can be sent using multiple messages, in which case each message will start with a User Data Header (UDH) containing segmentation information. Since UDH is part of the payload, the number of available characters per segment is lower: 153 for 7-bit encoding, 134 for 8-bit encoding and 67 for 16-bit encoding. The receiving handset is then responsible for reassembling the message and presenting it to the user as one long message. While the standard theoretically permits up to 255 segments,Ian Groves: "Mobile Systems", page 70, 79, 163–66. Chapman & Hall, 1998. 6 to 8 segment messages are the practical maximum, and long messages are often billed as equivalent to multiple SMS messages. Some providers have offered length-oriented pricing schemes for messages, however, the phenomenon is disappearing.
The aggregator model is based on multiple agreements with mobile carriers to exchange two-way SMS traffic into and out of the operator's SMSC, also known as local termination model. Aggregators lack direct access into the SS7 protocol, which is the protocol where the SMS messages are exchanged. SMS messages are delivered to the operator's SMSC, but not the subscriber's handset; the SMSC takes care of further handling of the message through the SS7 network.
Another type of SMS gateway provider is based on SS7 connectivity to route SMS messages, also known as international termination model. The advantage of this model is the ability to route data directly through SS7, which gives the provider total control and visibility of the complete path during SMS routing. This means SMS messages can be sent directly to and from recipients without having to go through the SMSCs of other mobile operators. Therefore, it is possible to avoid delays and message losses, offering full delivery guarantees of messages and optimized routing. This model is particularly efficient when used in mission-critical messaging and SMS used in corporate communications. Moreover, these SMS gateway providers are providing branded SMS services with masking but after misuse of these gateways most countries's Governments have taken serious steps to block these gateways.
Subscriber-originated messages are transported from a handset to a service center, and may be destined for mobile users, subscribers on a fixed network, or Value-Added Service Providers (VASPs), also known as application-terminated. Subscriber-terminated messages are transported from the service center to the destination handset, and may originate from mobile users, from fixed network subscribers, or from other sources such as VASPs.
On some carriers nonsubscribers can send messages to a subscriber's phone using an SMS gateway. Additionally, many carriers, including AT&T Mobility, T-Mobile USA, Sprint Nextel, and Verizon Wireless, offer the ability to do this through their respective websites.
For example, an AT&T subscriber whose phone number was 555-555-5555 would receive e-mails addressed to email@example.com as text messages. Subscribers can easily reply to these SMS messages, and the SMS reply is sent back to the original email address. Sending email to SMS is free for the sender, but the recipient is subject to the standard delivery charges. Only the first 160 characters of an email message can be delivered to a phone, and only 160 characters can be sent from a phone.
Text-enabled fixed-line handsets are required to receive messages in text format. However, messages can be delivered to nonenabled phones using Speech synthesis. BT trials mobile SMS to voice landline, January 2004, The Register.
Short messages can send binary content such as or logos, as well as Over-the-air programming (OTA) or configuration data. Such uses are a vendor-specific extension of the GSM specification and there are multiple competing standards, although Nokia's Smart message is common. An alternative way for sending such binary content is EMS messaging, which is standardized and not dependent on vendors.
SMS is used for M2M (Machine to Machine) communication. For instance, there is an LED display machine controlled by SMS, and some vehicle tracking companies use SMS for their data transport or telemetry needs. SMS usage for these purposes is slowly being superseded by GPRS services owing to their lower overall cost. GPRS is offered by smaller telco players as a route of sending SMS text to reduce the cost of SMS texting internationally., September 2006, SMStextnews
The connection between the terminal equipment and the transceiver can be realized with a serial cable (e.g., USB), a Bluetooth link, an infrared link, etc. Common AT commands include AT CMGS (send message), AT CMSS (send message from storage), AT CMGL (list messages) and AT CMGR (read message).
However, not all modern devices support receiving of messages if the message storage (for instance the device's internal memory) is not accessible using AT commands.
Mobile-terminated short messages can be used to deliver digital content such as news alerts, financial information, logos, and ring tones. The first premium-rate media content delivered via the SMS system was the world's first paid downloadable ringing tones, as commercially launched by Saunalahti (later Jippii Group, now part of Elisa Grous), in 1998. Initially only Nokia branded phones could handle them. By 2002 the ringtone business globally had exceeded $1 billion of service revenues, and nearly $5 billion by 2008. Today, they are also used to pay smaller payments online—for example, for file-sharing services, in mobile application stores, or VIP section entrance. Outside the online world, one can buy a bus ticket or beverages from ATM, pay a parking ticket, order a store catalog or some goods (e.g., discount movie DVDs), make a donation to charity, and much more.
Premium-rated messages are also used in Donors Message Service to collect money for charities and foundations. DMS was first launched at April 1, 2004, and is very popular in the Czech Republic. For example, the Czech people sent over 1.5 million messages to help South Asia recover from the 2004 Indian Ocean earthquake and tsunami.
The Value-added service provider (VASP) providing the content submits the message to the mobile operator's SMSC(s) using an TCP/IP protocol such as the short message peer-to-peer protocol (SMPP) or the External Machine Interface (EMI). The SMSC delivers the text using the normal Mobile Terminated delivery procedure. The subscribers are charged extra for receiving this premium content; the revenue is typically divided between the mobile network operator and the VASP either through revenue share or a fixed transport fee. Submission to the SMSC is usually handled by a third party.
Mobile-originated short messages may also be used in a premium-rated manner for services such as televoting. In this case, the VASP providing the service obtains a short code from the telephone network operator, and subscribers send texts to that number. The payouts to the carriers vary by carrier; percentages paid are greatest on the lowest-priced premium SMS services. Most information providers should expect to pay about 45 percent of the cost of the premium SMS up front to the carrier. The submission of the text to the SMSC is identical to a standard MO Short Message submission, but once the text is at the SMSC, the Service Center (SC) identifies the Short Code as a premium service. The SC will then direct the content of the text message to the VASP, typically using an IP protocol such as SMPP or EMI. Subscribers are charged a premium for the sending of such messages, with the revenue typically shared between the network operator and the VASP. Short codes only work within one country, they are not international.
An alternative to inbound SMS is based on long numbers (international number format, e.g. 44 762 480 5000), which can be used in place of short codes for SMS reception in several applications, such as TV voting, product promotions and campaigns. Long numbers work internationally, allow businesses to use their own numbers, rather than short codes, which are usually shared across many brands. Additionally, long numbers are nonpremium inbound numbers.
In the USA, A2P messages must be sent using a short code rather than a standard long code.
Satellite phone networks usually have web-based or email-based SMS portals where one can send free SMS to phones on that particular network.
In October 2005, researchers from Pennsylvania State University published an analysis of vulnerabilities in SMS-capable cellular networks. The researchers speculated that attackers might exploit the open functionality of these networks to disrupt them or cause them to fail, possibly on a nationwide scale. An Analysis of Vulnerabilities in SMS-Capable Cellular Networks: Exploiting Open Functionality in SMS-Capable Cellular Networks ( Website)
The only sure way of detecting and blocking spoofed messages is to screen incoming mobile-originated messages to verify that the sender is a valid subscriber and that the message is coming from a valid and correct location. This can be implemented by adding an intelligent routing function to the network that can query originating subscriber details from the HLR before the message is submitted for delivery. This kind of intelligent routing function is beyond the capabilities of legacy messaging infrastructure.