SMS

For other uses, see SMS (disambiguation).

For text messaging in general, see Text messaging.

An SMS message written on a Motorola Razr V3

E.161, a common mobile keypad alphabet layout

Short Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile devices exchange short text messages. An intermediary service can facilitate a text-to-voice conversion to be sent to landlines.<ref>Kelly, Heather (December 3, 2012). "OMG, The Text Message Turns 20. But has SMS peaked?". CNN. Archived from the original on January 27, 2021. Retrieved December 22, 2020.</ref>

SMS technology originated from radio telegraphy in radio memo pagers that used standardized phone protocols. These were defined in 1986 as part of the Global System for Mobile Communications (GSM) series of standards.<ref name="GSM 28/85">GSM Doc 28/85 "Services and Facilities to be provided in the GSM System" rev2, June 1985</ref> The first SMS message was sent on 3 December 1992, when Neil Papworth, a test engineer for Sema Group, sent "Merry Christmas" to the Orbitel 901 phone of colleague Richard Jarvis.<ref name="First SMS" /><ref>Kleinman, Zoe. "'Merry Christmas': 30 years of the text message". Archived from the original on 2022-12-03. Retrieved 2022-12-03.</ref><ref>"Vintage Mobiles". History of GSM. Orbitel 901 – the first GSM mobile and the first to receive a commercial SMS text message (1992). Archived from the original on 2016-01-26. Retrieved 2022-12-03.</ref> SMS rolled out commercially on many cellular networks that decade and became hugely popular worldwide as a method of text communication.<ref>Jennifer O Mahony; Jennifer Omahony (3 December 2012). "How SMS Changed the World". The Telegraph UK. Archived from the original on 18 November 2022. Retrieved 10 May 2020.</ref> By the end of 2010, SMS was the most widely used data application, with an estimated 3.5 billion active users, or about 80% of all mobile phone subscribers.

The service allows users to send and receive messages of up to 160 characters (when entirely alpha-numeric) to and from GSM mobiles. Although most SMS messages are sent from one mobile phone to another, support for the service has expanded to include other mobile technologies, such as CDMA networks and Digital AMPS.<ref name="Play GK Quiz:When First SMS Was Sent">"When First SMS Was Sent". Play GK Quiz. Archived from the original on December 1, 2017. Retrieved November 27, 2017.</ref>

Mobile marketing, a type of direct marketing, uses SMS.<ref>Black, Ken (September 13, 2016). "What is SMS Marketing?". wiseGEEK. Archived from the original on August 26, 2016. Retrieved September 28, 2016.</ref> The global SMS messaging business was estimated to be worth over US$240 billion in 2013, accounting for almost half of all revenue generated by mobile messaging.<ref>Portio Research. "Mobile Messaging Futures 2014-20148". Archived from the original on December 8, 2015. Retrieved September 28, 2016.</ref>

History

Initial concept

Adding text messaging functionality to mobile devices began in the early 1980s. The first action plan of the CEPT Group GSM was approved in December 1982, requesting that "The services and facilities offered in the public switched telephone networks and public data networks ... should be available in the mobile system."<ref>see GSM document 02/82, available on the GSM-SMG Archive DVD-ROM</ref> This plan included the exchange of text messages either directly between mobile stations, or transmitted via message handling systems in use at that time.<ref>These Message Handling Systems had been standardized in the ITU, see specifications X.400 series</ref>

The SMS concept was developed in the Franco-German GSM cooperation in 1984 by Friedhelm Hillebrand and Bernard Ghillebaert.<ref>See the book Hillebrand, Trosby, Holley, Harris: SMS the creation of Personal Global Text Messaging, Wiley 2010</ref> 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 for most brief communications.<ref name="latimesblogs.latimes.com">"Technology". May 3, 2009. Archived from the original on September 30, 2021. Retrieved June 14, 2015.</ref>

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.<ref>See GSM document 28/85rev.June 2, 85 and GSM WP1 document 66/86, available on the GSM-SMG Archive DVD-ROM</ref> 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.<ref>ETSI, TC-SMG. "Digital cellular telecommunications system (Phase 2+); Technical realization of the Short Message Service (SMS)" (PDF). etsi.org. Archived (PDF) from the original on 2023-12-12. Retrieved 2023-12-12.</ref>

Early development

The technical development of SMS was a multinational collaboration supporting the framework of standards bodies. Through these organizations the technology was made freely available to the whole world.<ref>See also Friedhelm Hillebrand "GSM and UMTS, the creation of Global Mobile Communication", Wiley 2002, chapters 10 and 16, ISBN 0-470-84322-5</ref>

The first proposal which initiated the development of SMS was made by a contribution of Germany and France in the GSM group meeting in February 1985 in Oslo.<ref>GSM document 19/85, available on the GSM-SMG Archive DVD-ROM</ref> 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 1985 document which was distributed to industry.<ref>GSM document 28/85r2, available on the GSM-SMG Archive DVD-ROM</ref> The input documents on SMS had been prepared by Friedhelm Hillebrand of Deutsche Telekom, with contributions from Bernard Ghillebaert of 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 electronic paging services used at the time that some in GSM might have had in mind.<ref>"So who really did create SMS?". Stephen Temple. February 24, 2013. Archived from the original on May 11, 2013. Retrieved April 6, 2013.</ref>

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,"<ref name="GSM 28/85"/> 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."<ref name="GSM 02.03">GSM TS 02.03 Archived 2008-12-05 at the Wayback Machine, Teleservices Supported by a GSM Public Land Mobile Network (PLMN).</ref> Here a rudimentary description of the three services was given:

1. Short message mobile-terminated (SMS-MT)/ Point-to-Point: the ability of a network to transmit a Short Message to a mobile phone. The message can be sent by phone or by a software application.
2. Short message mobile-originated (SMS-MO)/ Point-to-Point: the ability of a network to transmit a Short Message sent by a mobile phone. The message can be sent to a phone or to a software application.
3. Short message cell broadcast.

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 three 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 plan<ref>Document GSM IDEG 79/87r3, available on the GSM-SMG Archive DVD-ROM</ref> 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.<ref>GSM 03.40, WP4 document 152/87, available on the GSM-SMG Archive DVD-ROM</ref> 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.<ref>Finn Trosby, "the strange duckling of GSM SMS" Archived September 25, 2007, at the Wayback Machine, Telektronikk Vol.3 2004.</ref>

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.

Support in other architectures

The Mobile Application Part (MAP) of the SS7 protocol included support for the transport of Short Messages through the Core Network from its inception.<ref name="MAP phase 1">MAP phase 1 specification, available from the 3GPP Archived 2008-10-17 at the Wayback Machine web site.</ref> MAP Phase 2 expanded support for SMS by introducing a separate operation code for Mobile Terminated Short Message transport.<ref name="MAP phase 2">MAP phase 2 specification, available from the 3GPP Archived 2008-10-17 at the Wayback Machine web site.</ref> Since Phase 2, there have been no changes to the Short Message operation packages in MAP, although other operation packages have been enhanced to support CAMEL SMS control.

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,<ref name="CAMEL Phase 3">CAMEL Phase 3 specification, available from the 3GPP Archived 2007-05-01 at the Wayback Machine web site.</ref> while CAMEL Phase 4, as part of 3GPP Release 5 and onwards, provides the IN with the ability to control the Mobile Terminated service.<ref name="CAMEL Phase 4">CAMEL Phase 4 specification, also available from the 3GPP specification page.</ref> 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 Intelligent Network Application Part (INAP) of SS7.

Early implementations

The first SMS message<ref name="First SMS">Hppy bthdy txt! Archived 2007-01-20 at the Wayback Machine December 2002, BBC News.</ref> was sent over the Vodafone GSM network in the United Kingdom on 3 December 1992, from Neil Papworth of Sema Group (now Mavenir Systems) using a personal computer to Richard Jarvis of Vodafone using an Orbitel 901 handset. The text of the message was "Merry Christmas."<ref name="Neil Papworth">UK hails 10th birthday of SMS Archived 2011-04-29 at the Wayback Machine, December 2002, The Times of India.</ref>

The first commercial deployment of a short message service center (SMSC) was by Aldiscon part of Logica (now part of CGI) with Telia (now TeliaSonera) in Sweden in 1993,<ref>"First commercial deployment of Text Messaging (SMS)". Archived from the original on March 16, 2008. Retrieved May 24, 2017.</ref> followed by Fleet Call (now Nextel)<ref>US Department of Homeland Security. "Cellular Technologies" (PDF). Electronic Frontier Foundation). Archived from the original (PDF) on May 24, 2012.</ref> in the US, Telenor in Norway<ref>"Our history in Norway". Telenor Group. 1993. Archived from the original on 3 December 2022. Retrieved 3 December 2022. Telenor leads in establishing GSM (2G) – the SMS service was a part of this platform</ref> and BT Cellnet (now O2 UK)<ref>"BT unveils new mobile brand". BBC News Online. September 3, 2001. Archived from the original on April 9, 2022. Retrieved November 13, 2021.</ref> 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, an engineer at Nokia at the time, the Nokia 2010, which was released in January 1994, was the first mobile phone to support composing SMSes easily.<ref>Nael, Merili (June 30, 2015). "Suri tekstisõnumite looja Matti Makkonen" [Creator of text messages Matti Makkonen died]. Err.ee (in eesti). Eesti Rahvusringhääling. Archived from the original on March 4, 2016. Retrieved July 27, 2015.</ref>

Initial growth was slow, with customers in 1995 sending on average only 0.4 messages per GSM customer per month.<ref name="gsmworld">GSM World press release Archived February 15, 2002, at the Wayback Machine</ref> 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.<ref name="First SMS" />

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,<ref name="gsmworld"/> and on Christmas Day 2006, over 205 million messages were sent in the UK alone.<ref name=2b>Crystal, David (July 5, 2008). "2b or not 2b?". Guardian Unlimited. London, UK. Archived from the original on July 8, 2008. Retrieved July 8, 2008.</ref>

Text messaging outside GSM

A Siemens wireless landline telephone that is capable of SMS

SMS was originally designed as part of GSM, but is now available on a wide range of networks, including 3G networks. However, not all text messaging systems use SMS, and some notable alternative implementations of the concept include J-Phone's SkyMail and NTT Docomo's Short Mail, both in Japan. Email messaging from phones, as popularized by NTT Docomo's i-mode and the RIM BlackBerry, also typically uses standard mail protocols such as SMTP over TCP/IP.

SMS today

SMS messages sent monthly in the U.S. from 2001 to 2008 (in billions)

In 2010, 6.1 trillion (6.1 × 10¹²) SMS text messages were sent,<ref name="itu">"The World Today – The rise of 3G" (PDF). Archived (PDF) from the original on 2022-12-03. Retrieved 2022-12-03.</ref> which is an average of 193,000 SMS per second. SMS has become a large commercial industry, earning $114.6 billion globally in 2010.<ref>Matthews, Charles H. (Economist) (2015). Innovation and entrepreneurship : a competency framework. Brueggemann, Ralph. (First ed.). New York. ISBN 978-0-415-74252-8. OCLC 893453493.{{cite book}}: CS1 maint: location missing publisher (link)</ref> The global average price for an SMS message is US$0.11, while mobile networks charge each other interconnect fees of at least US$0.04 when connecting between different phone networks.

In 2015, the actual cost of sending an SMS in Australia was found to be $0.00016 per SMS.<ref>Han, Esther (May 6, 2015). "Cheaper mobile calls and text as ACCC moves to slash wholesale fees". Archived from the original on May 8, 2015. Retrieved May 6, 2015 – via The Age.</ref>

In 2014, Caktus Group<ref>"Caktus Group". Archived from the original on 2017-02-22. Retrieved 2017-02-21.</ref> developed the world's first SMS-based voter registration system in Libya. As of February 2015 more than 1.5 million people have registered using that system, providing Libyan voters with unprecedented access to the democratic process.<ref>"Libya's Election Ushers in New Voter Tech". World Policy Institute. Archived from the original on July 7, 2014. Retrieved June 14, 2015.</ref>

SMS is being increasingly challenged by Internet Protocol-based messaging services such as RCS, Apple's iMessage, Signal, Facebook Messenger/WhatsApp, Telegram, Viber, WeChat (in China) and Line (in Japan), available on smart phones with internet connections.<ref>"The death of SMS is exaggerated". 13 June 2011. Archived from the original on 9 January 2012. Retrieved 25 November 2011.</ref> For example, between 2010 and 2022, SMS telecom revenue in India dropped 94 percent, while "revenue share per user from data usage...grew over 10 times."<ref>"Online apps slash telecoms revenue: 80% decline in voice calls, 94% drop in SMS in 10 years". Hindustan Times. 2023-07-09. Archived from the original on 2023-11-11. Retrieved 2023-11-11.</ref>

SMS Enablement

SMS enablement allows individuals to send an SMS message to a business phone number (traditional landline) and receive a SMS in return. Providing customers with the ability to text to a phone number allows organizations to offer new services that deliver value. Examples include chat bots, and text enabled customer service and call centers.

Technical details

GSM

Main article: Short message service technical realisation (GSM)

The Short Message Service—Point to Point (SMS-PP)—was originally defined in GSM recommendation 03.40, which is now maintained in 3GPP as TS 23.040.<ref name="GSM 03.40">"Specification # 03.40". Archived from the original on 3 December 2022. Retrieved 3 December 2022.</ref><ref>"Specification # 23.040". Archived from the original on 7 December 2022. Retrieved 3 December 2022.</ref> GSM 03.41 (now 3GPP TS 23.041) defines the Short Message Service—Cell Broadcast (SMS-CB), which allows messages (advertising, public information, etc.) to be broadcast to all mobile users in a specified geographical area.<ref name="GSM 03.41">"Specification # 03.41". Archived from the original on 3 December 2022. Retrieved 3 December 2022.</ref><ref>"Specification # 23.041". Archived from the original on 3 December 2022. Retrieved 3 December 2022.</ref>

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.<ref>Gil Held: "Data over Wireless Networks." pages 105–11, 137–38. Wiley, 2001.</ref> 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", so there are no guarantees that a message will actually be delivered to its recipient, but delay or complete loss of a message is uncommon, typically affecting less than 5 percent of messages.<ref>Oliver, Earl, Design and Implementation of a Short Message Service Data Channel for Mobile Systems (PDF), archived (PDF) from the original on January 26, 2022, retrieved March 14, 2022</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#<ref>"Text Message Tips (not sent or received)". community.o2.co.uk. December 9, 2018. Archived from the original on September 28, 2021. Retrieved September 28, 2021.</ref> 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.

Message size

Transmission of short messages between the SMSC and the handset is done whenever using the Mobile Application Part (MAP) of the SS7 protocol.<ref>Amri, Kuross. "Communication Networks". Archived from the original on May 11, 2016. Retrieved October 5, 2013.</ref> Messages are sent with the MAP MO- and MT-ForwardSM operations, whose payload length is limited by the constraints of the signaling protocol to precisely 140 bytes (140 bytes * 8 bits / byte = 1120 bits).

Short messages can be encoded using a variety of alphabets: the default GSM 7-bit alphabet, the 8-bit data alphabet, and the 16-bit UCS-2 alphabet.<ref name="3GPP 23.038">3GPP TS 23.038 Archived 2007-06-16 at the Wayback Machine, Alphabets and language-specific information.</ref> Depending on which alphabet the subscriber has configured in the handset, this leads to the maximum individual short message sizes of 160 7-bit characters, 140 8-bit characters, or 70 16-bit characters. GSM 7-bit alphabet support is mandatory for GSM handsets and network elements,<ref name="3GPP 23.038"/> but characters in languages such as Hindi, Arabic, Chinese, Korean, Japanese, or Cyrillic alphabet languages (e.g., Russian, Ukrainian, Serbian, Bulgarian, etc.) must be encoded using the 16-bit UCS-2 character encoding (see Unicode). Routing data and other metadata is additional to the payload size.

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,<ref>Groves, Ian (1998). Mobile systems (1st ed.). London: Springer. pp. 70, 79, 163–66. ISBN 978-1-4615-6377-8. OCLC 847640648. Archived from the original on 2024-01-11. Retrieved 2021-09-23.</ref> 10 segments is the practical maximum with some carriers,<ref>"Does Twilio support concatenated SMS messages or messages over 160 characters?". Twilio Support. Archived from the original on 3 December 2022. Retrieved 3 December 2022. when sending very long SMS messages (longer than 10 segments with Unicode characters) some mobile carriers may have trouble handling these messages.</ref> and long messages are often billed as equivalent to multiple SMS messages. In some cases 127 segments are supported,<ref>"Simplifying Unicode punctuation for SMS". ssb22.user.srcf.net. Archived from the original on July 15, 2021. Retrieved July 15, 2021.</ref> but software limitations in some SMS applications do not permit this. Some providers have offered length-oriented pricing schemes for messages, although that type of pricing structure is rapidly disappearing.

Gateway providers

SMS gateway providers facilitate SMS traffic between businesses and mobile subscribers, including SMS for enterprises, content delivery, and entertainment services involving SMS, e.g. TV voting. Considering SMS messaging performance and cost, as well as the level of messaging services, SMS gateway providers can be classified as aggregators or SS7 providers.

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' governments have taken serious steps to block these gateways.

Interconnectivity with other networks

Message Service Centers communicate with the Public Land Mobile Network (PLMN) or PSTN via Interworking and Gateway MSCs.

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 Email-to-SMS gateway. Additionally, many carriers, including AT&T Mobility, T-Mobile USA,<ref>"t-zones text messaging: send and receive messages with mobile text messaging". T-mobile.com. Archived from the original on September 17, 2008. Retrieved September 18, 2008.</ref> Sprint,<ref>"Support – How do I compose and send a text message to a Sprint or Nextel customer from email?". Support.sprintpcs.com. Archived from the original on October 20, 2008. Retrieved September 18, 2008.</ref> and Verizon Wireless,<ref>"Answers to FAQs – Verizon Wireless Support". Support.vzw.com. Archived from the original on September 9, 2008. Retrieved September 18, 2008.</ref> 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 emails addressed to 5555555555@txt.att.net 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. However, longer messages may be broken up into multiple texts, depending upon the telephone service provider.<ref>"Is there a maximum SMS message length?". TextAnywhere. Archived from the original on May 8, 2017. Retrieved May 8, 2017.</ref><ref>Hill, Simon; Revilla, Andre (28 April 2022). "How to send a text message from your email account". Digital Trends. Archived from the original on 3 December 2022. Retrieved 3 December 2022. Keep in mind that if you're trying to send a message that's more than 160 characters long, it will often be sent through the Multimedia Message Service (MMS).</ref>

Text-enabled fixed-line handsets are required to receive messages in text format. However, messages can be delivered to non enabled phones using text-to-speech conversion.<ref name="Voice SMS">Leyden, John (January 2004). "BT trials mobile SMS to voice landline". The Register. Archived from the original on June 29, 2017. Retrieved May 8, 2017.</ref>

Short messages can send binary content such as ringtones 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 Messaging is common.

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.<ref name="GPRS SMS">Ewan (September 1, 2006). "10pText.co.uk help you text internationally for 10p/text". SMStextnews. Archived from the original on March 4, 2016. Retrieved May 8, 2017.</ref>

AT commands

Many mobile and satellite transceiver units support the sending and receiving of SMS using an extended version of the Hayes command set. The extensions were standardised as part of the GSM Standards and extended as part of the 3GPP standards process.<ref>"Use of Data Terminal Equipment – Data Circuit terminating Equipment (DTE – DCE) interface for Short Message Service (SMS) and Cell Broadcast Service (CBS)". Archived from the original on February 16, 2020. Retrieved July 1, 2019.</ref>

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).<ref name="SMS AT extensions">"SMS Tutorial: Introduction to AT Commands, Basic Commands and Extended Commands". Archived from the original on May 9, 2008. Retrieved June 14, 2015.</ref>

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.<ref>Agarwal, Tarun (2019-09-18). "What are AT Commands : Different Types, and Their List". ElProCus – Electronic Projects for Engineering Students. Archived from the original on 2022-05-16. Retrieved 2022-07-11.</ref>

Premium-rated short messages

See also: Reverse SMS billing and Short code

Short messages may be used normally to provide premium rate services to subscribers of a telephone network.

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 Group), 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 US$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.

The Value-added service provider (VASP) providing the content submits the message to the mobile operator's SMSC(s) using a 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, such as "+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.

Threaded SMS

Threaded SMS is a visual styling orientation of SMS message history that arranges messages to and from a contact in chronological order on a single screen.

It was first invented by a developer working to implement the SMS client for the BlackBerry, who was looking to make use of the blank screen left below the message on a device with a larger screen capable of displaying far more than the usual 160 characters, and was inspired by threaded Reply conversations in email.<ref>USPTO – US Patent 7028263 2001 Archived 2024-01-11 at the Wayback Machine</ref>

Visually, this style of representation provides a back-and-forth chat-like history for each individual contact.<ref>From Phone Scoop definitions – Threaded Messaging definition (Phone Scoop) Archived 2013-02-03 at the Wayback Machine – Retrieved December 29, 2012</ref> Hierarchical-threading at the conversation-level (as typical in blogs and on-line messaging boards) is not widely supported by SMS messaging clients. This limitation is due to the fact that there is no session identifier or subject-line passed back and forth between sent and received messages in the header data (as specified by SMS protocol) from which the client device can properly thread an incoming message to a specific dialogue, or even to a specific message within a dialogue.

Most smart phone text-messaging-clients are able to create some contextual threading of "group messages" which narrows the context of the thread around the common interests shared by group members. On the other hand, advanced enterprise messaging applications which push messages from a remote server often display a dynamically changing reply number (multiple numbers used by the same sender), which is used along with the sender's phone number to create session-tracking capabilities analogous to the functionality that cookies provide for web-browsing. As one pervasive example, this technique is used to extend the functionality of many Instant Messenger (IM) applications such that they are able to communicate over two-way dialogues with the much larger SMS user-base.<ref>"Whitepaper: Market Opportunities for Text and MMS Messaging" ABI Research, 2011</ref> In cases where multiple reply numbers are used by the enterprise server to maintain the dialogue, the visual conversation threading on the client may be separated into multiple threads.

Application-to-person (A2P) SMS

While SMS reached its popularity as a person-to-person messaging, another type of SMS is growing fast: application-to-person (A2P) messaging. A2P is a type of SMS sent from a subscriber to an application or sent from an application to a subscriber. It is commonly used by businesses, such as banks, e-gaming, logistic companies, e-commerce, to send SMS messages from their systems to their customers.<ref>"What is A2P (Application-to-person) SMS Messaging? | Glossary". www.infobip.com. Archived from the original on January 25, 2017. Retrieved April 13, 2019.</ref>

In the US, carriers have traditionally preferred that A2P messages must be sent using a short code rather than a standard long code.<ref>"Long Code Vs Short Code – What's The Difference?". Archived from the original on January 11, 2024. Retrieved September 23, 2015.</ref> However, recently multiple US carriers, including Verizon have announced plans to officially support A2P messages over long codes.<ref>"Commercial Long Code SMS Product and Fee Structure Changes on Verizon". Archived from the original on October 18, 2019. Retrieved October 17, 2019.</ref> In the United Kingdom A2P messages can be sent with a dynamic 11 character sender ID; however, short codes are used for OPTOUT commands.

Satellite phone networks

All commercial satellite phone networks except ACeS and OptusSat support SMS. While early Iridium handsets only support incoming SMS, later models can also send messages. The price per message varies for different networks. Unlike some mobile phone networks, there is no extra charge for sending international SMS or to send one to a different satellite phone network. SMS can sometimes be sent from areas where the signal is too poor to make a voice call.

Satellite phone networks usually have web-based or email-based SMS portals where one can send free SMS to phones on that particular network.

Unreliability

Unlike dedicated texting systems like the Simple Network Paging Protocol and Motorola's ReFLEX protocol,<ref>"Motorola's ReFLEX Protocol Delivers Wireless Data With Unparelleled Nationwide Network Coverage". July 17, 2012. Archived from the original on July 17, 2012.</ref> SMS message delivery is not guaranteed, and many implementations provide no mechanism through which a sender can determine whether an SMS message has been delivered in a timely manner.<ref name="cellular-news">"Report Says That SMS is Not Ideal for Emergency Communications". cellular-news. Archived from the original on January 25, 2015. Retrieved June 14, 2015.</ref> SMS messages are generally treated as lower-priority traffic than voice, and various studies have shown that around 1% to 5% of messages are lost entirely, even during normal operation conditions, and others may not be delivered until long after their relevance has passed.<ref>Text Message Delivery Time and Reliability Archived July 12, 2011, at the Wayback Machine</ref> The use of SMS as an emergency notification service in particular has been questioned.<ref name="cellular-news"/>

Vulnerabilities

An example of a phishing attack through SMS, showing a fake message and URL claiming to be from Apple

See also: Mobile security § Attacks based on SMS and MMS

The Global Service for Mobile communications (GSM), with the greatest worldwide number of users, succumbs to several security vulnerabilities. In the GSM, only the airway traffic between the Mobile Station (MS) and the Base Transceiver Station (BTS) is optionally encrypted with a weak and broken stream cipher (A5/1 or A5/2). The authentication is unilateral and also vulnerable. There are also many other security vulnerabilities and shortcomings.<ref>Solutions to the GSM Security Weaknesses Archived 2014-08-10 at the Wayback Machine, Proceedings of the 2nd IEEE International Conference on Next Generation Mobile Applications, Services, and Technologies (NGMAST2008), pp. 576–581, Cardiff, UK, September 2008, arXiv:1002.3175</ref> Such vulnerabilities are inherent to SMS as one of the superior and well-tried services with a global availability in the GSM networks. SMS messaging has some extra security vulnerabilities due to its store-and-forward feature, and the problem of fake SMS that can be conducted via the Internet. When a user is roaming, SMS content passes through different networks, perhaps including the Internet, and is exposed to various vulnerabilities and attacks. Another concern arises when an adversary gets access to a phone and reads the previous unprotected messages.<ref>SSMS – A Secure SMS Messaging Protocol for the M-Payment Systems Archived 2016-04-09 at the Wayback Machine, Proceedings of the 13th IEEE Symposium on Computers and Communications (ISCC'08), pp. 700–705, July 2008 arXiv:1002.3171</ref>

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.<ref>An Analysis of Vulnerabilities in SMS-Capable Cellular Networks: Exploiting Open Functionality in SMS-Capable Cellular Networks Archived 2009-05-30 at the Wayback Machine (Website) Archived December 10, 2005, at the Wayback Machine</ref>

SMS spoofing

Main article: SMS spoofing

The GSM industry has identified a number of potential fraud attacks on mobile operators that can be delivered via abuse of SMS messaging services. The most serious threat is SMS Spoofing, which occurs when a fraudster manipulates address information in order to impersonate a user that has roamed onto a foreign network and is submitting messages to the home network. Frequently, these messages are addressed to destinations outside the home network—with the home SMSC essentially being "hijacked" to send messages into other networks.

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 home location register (HLR) before the message is submitted for delivery. This kind of intelligent routing function is beyond the capabilities of legacy messaging infrastructure.<ref>"An overview on how to stop SMS Spoofing in mobile operator networks (September 9, 2008)". Archived from the original on September 26, 2008. Retrieved September 12, 2008.</ref>

Limitation

In an effort to limit telemarketers who had taken to bombarding users with hordes of unsolicited messages, India introduced new regulations in September 2011, including a cap of 3,000 SMS messages per subscriber per month, or an average of 100 per subscriber per day.<ref>Nirmala Ganapathy (September 27, 2011). "3,000 SMS a Month Limit in India From Today". Straits Times Indonesia. Archived from the original on February 4, 2013. Retrieved November 10, 2011.</ref> Due to representations received from some of the service providers and consumers, TRAI (Telecom Regulatory Authority of India) has raised this limit to 200 SMS messages per SIM per day in case of prepaid services, and up to 6,000 SMS messages per SIM per month in case of postpaid services with effect from November 1, 2011.<ref>"TRAI extends the 100 SMS per day per SIM limit to 200 SMS per day per SIM" (PDF). Archived from the original (PDF) on November 11, 2011. Retrieved November 16, 2011.</ref> However, it was ruled unconstitutional by the Delhi high court, but there are some limitations.<ref>Special Correspondent (January 26, 2012). "News / National : TRAI cap on SMS goes". The Hindu. Archived from the original on December 12, 2012. Retrieved February 24, 2013.</ref>

Flash SMS

A Flash SMS is a type of SMS that appears directly on the main screen without user interaction and is not automatically stored in the inbox.<ref>"SMS types on routomessaging.com". Archived from the original on May 5, 2013. Retrieved February 20, 2016.</ref> It can be useful in emergencies, such as a fire alarm or cases of confidentiality, as in delivering one-time passwords.<ref>"Flash SMS". Archived from the original on August 18, 2015. Retrieved June 14, 2015.</ref>

Silent SMS

In 2010 Germany, almost half a million "silent SMS" messages were sent by the federal police, customs and the secret service "Verfassungsschutz" (offices for protection of the constitution).<ref>Reitman, Rainey (10 January 2012). "Privacy Roundup: Mandatory Data Retention, Smart Meter Hacks, and Law Enforcement Usage of "Silent SMS"". Electronic Frontier Foundation. Archived from the original on 15 February 2015. Retrieved 15 February 2015.</ref><ref>"Zoll, BKA und Verfassungsschutz verschickten 2010 über 440.000 "stille SMS" | heise online". Heise.de. Archived from the original on March 2, 2013. Retrieved February 24, 2013.</ref> These silent messages, also known as "silent TMS", "stealth SMS", "stealth ping" or "Short Message Type 0",<ref>"3GPP TS 51.010-1 version 12.5.0 Release 12" (PDF). ETSI. September 2015. pp. 3418–3423. Archived (PDF) from the original on April 24, 2017. Retrieved April 23, 2017.</ref> are used to locate a person and thus to create a complete movement profile. They do not show up on a display, nor trigger any acoustical signal when received. Their primary purpose was to deliver special services of the network operator to any cell phone.

See also

• Process driven messaging service
• Comparison of mobile phone standards
• Instant messaging
• Text messaging
• Thumbing
• GSM 03.40
• Data Coding Scheme
• Enhanced Messaging Service (EMS)
• Multimedia Messaging Service (MMS)
• Rich Communication Services (RCS)
• Short Message Service Center (SMSC)
• Short message service technical realisation (GSM)
• SMS gateway (sending text to or from devices other than phones)
• SMS hubbing
• SMS home routing
• SMS language

External links

• 3GPP – the organization that maintains the SMS specification
• ISO Standards (In Zip file format)
• GSM 03.38 to Unicode – how the GSM 7-bit default alphabet characters map into Unicode