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This article is about the communication protocol technology. For information about text messaging, see Text messaging. For other uses, see SMS (disambiguation).

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An SMS being received






E.161, the most common mobile keypad alphabet layout





Short Message Service (SMS) is the text communication service component of phone or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices. SMS text messaging is the most widely used data application in the world, with 2.4 billion active users, or 74% of all mobile phone subscribers.^{[citation needed]}
The term SMS is used as a synonym for all types of short text
messaging, as well as the user activity itself, in many parts of the
world.
SMS as used on modern handsets was originated from radio telegraphy in radio memo pagers using standardized phone protocols and later defined as part of the Global System for Mobile Communications (GSM) series of standards in 1985^[1] as a means of sending messages of up to 160 characters^[2], to and from GSM mobile handsets.^[3] Since then, 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.^{[citation needed]} Most SMS messages are mobile-to-mobile text messages, though the standard supports other types of broadcast messaging as well.

Contents [hide] 1 History 1.1 Initial concept 1.2 Early development 1.3 Support in other architectures 1.4 Early implementations 1.5 Text messaging outside GSM 1.6 SMS today 1.7 Consumer vs. business SMS 2 Technical details 2.1 GSM 2.2 Message size 2.3 SMS Gateway providers 2.4 Interconnectivity with other networks 2.5 AT commands 2.6 Premium-rated short messages 2.7 SMS in satellite phone networks 2.8 Vulnerabilities 2.8.1 SMS spoofing 3 Standardization 4 See also 5 References 6 External links

//

[edit] History


[edit] Initial concept



SMS messages sent monthly in USA (billion)





The idea of adding text messaging to the services of mobile users
was latent in many communities of mobile communication services at the
beginning of the 1980s. The first action plan of the CEPT Group GSM,
approved in December 1982, requested "The services and facilities
offered in the public switched telephone networks and public data
networks... should be available in the mobile system".^[4] This target includes the exchange of text messages either directly between mobile stations, or transmitted via Message Handling Systems widely in use since the beginning of the 1980s.^[5]
The SMS concept was developed in the Franco-German GSM cooperation
in 1984 by Friedhelm Hillebrand and Bernard Ghillebaert and Oculy
Silaban.^[6] The innovation in SMS is Short.
The GSM is optimized for telephony, since this was identified as its
main application. The key idea for SMS was to use this
telephony-optimized system, and to transport messages on the signaling
paths needed to control the telephony traffic during time periods when
no signaling 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 140 bytes, or 160 7-bit characters), so that the messages
could fit into the existing signaling formats.
This concept allowed SMS to be implemented in every mobile station,
by updating its software. This concept was instrumental for the
implementation of SMS in every mobile station ever produced and in
every network from early days. Hence, a large base of SMS capable
terminals and networks existed when the users began to utilize the SMS.^[7]
A new network element required was a specialized Short Message Service
Center, and enhancements were required to the radio capacity and
network transport infrastructure to accommodate growing SMS traffic.
[edit] Early development


The technical development of SMS was a multinational collaboration
supporting the framework of standards bodies, and through these
organizations the technology was made freely available to the whole
world. This is described and supported by evidence in the following
sections.^[8]
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^[9].
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.^[10] The input documents on SMS had been prepared by Friedhelm Hillebrand (Deutsche Telekom) with contributions from Bernard Ghillebaert (France Télécom).
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",^[1] 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".^[11] 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 together) and GSM 03.41 (cell broadcast).
WP4 created a Drafting Group Message Handling (DGMH), which was
responsible for the specification of SMS. It was chaired by Finn Trosby
(Telenor). DGMH had about five to eight participants (Finn Trosby
mentions as a contributor Alan Cox of Vodafone). The first action plan^[12]
mentions for the first time the Technical Specification 03.40
“Technical realisation of the Short Message Service”. Responsible
editor was Finn Trosby. The first draft of the technical specification
was completed in November 1987 ^[13] A comprehensive description ^[14].
The work on the draft specification continued in the following few
years, where Kevin Holley of Cellnet (now Telefonica 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.
[edit] 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.^[15] MAP Phase 2 expanded support for SMS by introducing a separate operation code for Mobile Terminated Short Message transport.^[16]
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,^[17]
while CAMEL Phase 4, as part of 3GPP Release 5 and onwards, provides
the IN with the ability to control the Mobile Terminated service.^[18] 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.
[edit] Early implementations


The first SMS message^[19] was sent over the Vodafone GSM network in the United Kingdom on 3 December 1992, from Neil Papworth of Sema Group (now Airwide Solutions) using a personal computer to Richard Jarvis of Vodafone using an Orbitel 901 handset. The text of the message was "Happy Christmas".^[20]
The first commercial deployment of a Short Message Service Center (SMSC) was by Aldiscon (now Acision) with TeliaSonera in Sweden in 1993^[21], followed by Fleet Call (now Nextel)^{[citation needed]} in the US, Telenor in Norway^{[citation needed]} and BT Cellnet (now O2 UK)^{[citation needed]}
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 1993. It should be noted that 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.
Initial growth was slow, with customers in 1995 sending on average only 0.4 messages per GSM customer per month.^[22]
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^{[citation needed]}.
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,^[22] and by Christmas Day 2006, over 205 million messages were sent in the UK alone.^[23]
It is also alleged that the fact that roaming customers, in the
early days, rarely received bills for their SMSs after holidays abroad
had a boost on text messaging as an alternative to voice calls.^{[citation needed]}
[edit] Text messaging outside GSM


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.
[edit] SMS today


In 2008, 4.1 trillion SMS text messages were sent. SMS has become a
massive commercial industry, worth over 81 billion dollars globally as
of 2006.^[24]
The global average price for an SMS message is 0.11 USD, while the cost
to providers approaches zero. Mobile networks charge each other
so-called interconnect fees of at least 0.04 USD (£0.03) when
connecting between different phone networks.^[25]
[edit] Consumer vs. business SMS


Companies looking to operate a mobile channel to interact with their
customers have to consider the quality of service their mobile service
provider can offer. In comparison to enterprise SMS, common consumer
SMS has some shortcomings:
Consumer SMSBusiness SMS

Unreliable	Timely delivery
Immeasurable	Measurable via delivery notifications
Subject to high levels of message loss and delay	No message loss, full transparency and security through end-to-end delivery
Insecure transmission routes	Viable for all types of mobile interaction: B2B, B2C, C2B, C2C
Viable for person-to-person communications only

Some providers offer delivery notifications, which are directly
sourced from the end-users handset, to overcome some of the reliability
problems associated with consumer SMS. To further enhance the
transmission of text some messaging providers also recently started
offering service level agreements and/or also delivery guarantees.
[edit] Technical details


[edit] GSM

1. mobile operator networks (September 9, 2008)
   

[edit] External links

Wikimedia Commons has media related to: Short message service

• 3GPP - The organization that maintains the SMS specification.
  
• SMS, the strange duckling of GSM
  
• ISO Standards (In Zip file format)
  
• GSM 03.38 to Unicode - the official GSM
  

[hide]v • d • eURI scheme

Official	aaa · aaas · acap · cap · cid · crid · data · dav · dict · dns · fax · file · ftp · geo · go · gopher · h323 · http · https · im · imap · Info · ldap · mailto · mid · news · nfs · nntp · pop · pres · rtsp · sip · sips · snmp · tag · tel · telnet · urn · wais · xmpp
Unofficial	about · afp · aim · apt · bolo · bzr · callto · cel · cvs · daap · disk · ed2k · feed · fish · gg · git · gizmoproject · iax2 · irc · ircs · itms · lastfm · ldaps · magnet · mms · msnim · postal2 · psyc · rsync · secondlife · skype · spotify · ssh · svn · sftp · smb · sms · soldat · steam · unreal · ut2004 · view-source · vzochat · webcal · winamp · wyciwyg · xfire · ymsgr

Main article: Short message service technical realisation (GSM)

The Short Message Service - Point to Point (SMS-PP) is defined in GSM recommendation 03.40.^[3] GSM 03.41 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.^[26] 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.^[27]
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.
Users may request delivery reports to confirm that messages reach the
intended recipients, either via the SMS settings of most modern phones,
or by prefixing each message with *0# or *N#.
[edit] 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. 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 octets (140 octets = 140 * 8 bits = 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 UTF-16 alphabet.^[28]
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 (including
spaces). GSM 7-bit alphabet support is mandatory for GSM handsets and
network elements,^[28]
but characters in languages such as Arabic, Chinese, Korean, Japanese
or Cyrillic alphabet languages (e.g. Russian, Serbian, Bulgarian, etc.)
must be encoded using the 16-bit UTF-16 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,^[29]
6 to 8 segment messages are the practical maximum, and long messages
are often billed as equivalent to multiple SMS messages. See Concatenated SMS
for more information. Some providers have offered length-oriented
pricing schemes for SMSs, however, the phenomenon is disappearing.
[edit] SMS Gateway providers

This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (June 2008)

SMS gateway providers facilitate SMS traffic between businesses and
mobile subscribers, including mission-critical messages, 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 2-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’s 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.
[edit] 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 non-subscribers can send messages to a subscriber's phone using an Email-to-SMS gateway. Additionally, many carriers, including AT&T, T-Mobile^[30], Sprint^[31], and Verizon Wireless^[32],
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 from 5555555555@txt.att.net as text messages.
Sending a message this way is free, but subject to the normal length
limit.
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.^[33]
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. 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 due to their lower overall cost^{[citation needed]}. GPRS is offered by smaller telco players as a route of sending SMS text to reduce the cost of SMS texting internationally.^[34]
[edit] AT commands


Many mobile and satellite transceiver units support the sending and receiving of SMS using an extended version of the Hayes command set, a specific command language originally developed for the Hayes Smartmodem 300-baud modem in 1977.^{[citation needed]}
The connection between the terminal equipment and the transceiver can be realized with a serial cable (i.e. 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).^[35]
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.
[edit] Premium-rated short messages


Short messages may be used 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 in 1998, only Nokia branded phones
could accept this type of external music installment. By 2002, the ring
tone business globally had exceeded one billion dollars of service
revenues and in 2008 the 'basic ringing tone' industry was worth nearly
5 billion dollars.
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, and the amount is typically divided between the mobile network operator and the VASP either through revenue share or a fixed transport fee.
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, and the
percentages paid are greatest on the lowest-priced premium SMS
services. Most information providers should expect to pay about 45% 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. Limitations of short codes include the
limitation to national borders (short codes have to be activated in
each country where the campaign takes place), as well as being
expensive to sign up together with mobile operators.
An alternative to inbound SMS is based on long numbers
(international number format, e.g. +44 7624 805000), 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
are internationally available, as well as enabling businesses to have
their own numbers, rather than short codes which are usually shared
across a lot of brands. Additionally, long numbers are non-premium inbound numbers.See also: Reverse SMS billing, Mobile search, and Short code

[edit] SMS in satellite phone networks


All commercial satellite phone networks except ACeS and OptusSat support SMS^{[citation needed]}. 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.
[edit] Vulnerabilities


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^[36]. 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 ^[37].
In October 2005, researchers from Pennsylvania State University published an analysis of vulnerabilities in SMS-capable cellular networks.^[38]
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.
[edit] 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 of threats is SMS Spoofing. SMS Spoofing
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 HLR before the message is submitted for delivery. This
kind of intelligent routing function is beyond the capabilities of
legacy messaging infrastructure.^[39]
[edit] Standardization

This section requires expansion.

[edit] See also

• Comparison of mobile phone standards
  
• SMS language
  
• Telegram
  
• Text messaging
  
• Thumbing
  
• Short Message Service Center (SMSC)
  
• Short message service technical realisation (GSM)
  
• SMS gateways (sending text to or from devices other than phones)
  
• SMS hubbing
  
• Multimedia Messaging Service
  

[edit] References

1. ^ ^{a b} GSM Doc 28/85 "Services and Facilities to be provided in the GSM System" rev2, June 1985
   
2. ^ LA Times: Why text messages are limited to 160 characters
   
3. ^ ^{a b} GSM 03.40 Technical realization of the Short Message Service (SMS).
   
4. ^ see GSM document 02/82 available in the ETSI archive
   
5. ^ These Message Handling Systems had been standardized in the ITU, see specifications X.400 series
   
6. ^ See the book Hillebrand, Trosby, Holley, Harris: SMS the creation of Personal Global Text Messaging, Wiley 2010
   
7. ^ See GSM document 28/85rev.2 of June 85 and GSM WP1 document 66/86 available in the ETSI archive
   
8. ^ See also Friedhelm Hillebrand "GSM and UMTS, the creation of Global Mobile Communication", Wiley 2002, chapters 10 and 16, ISBN 0470 84322 5
   
9. ^ GSM document 19/85, available in the ETSI archive
   
10. ^ GSM document 28/85r2, available in the ETSI archive
    
11. ^ GSM TS 02.03, Teleservices Supported by a GSM Public Land Mobile Network (PLMN).
    
12. ^ Document GSM IDEG 79/87r3, available in the ETSI archive
    
13. ^ GSM 03.40, WP4 document 152/87, available in the ETSI archive
    
14. ^ Finn Trosby, "the strange duckling of GSM SMS", Telektronikk Vol.3 2004.
    
15. ^ MAP phase 1 specification, available from the 3GPP web site.
    
16. ^ MAP phase 2 specification, available from the 3GPP web site.
    
17. ^ CAMEL Phase 3 specification, available from the 3GPP web site.
    
18. ^ CAMEL Phase 4 specification, also available from the 3GPP specification page.
    
19. ^ Hppy bthdy txt! December 2002, BBC News.
    
20. ^ UK hails 10th birthday of SMS, December 2002, The Times of India.
    
21. ^ First commercial deployment of Text Messaging (SMS)
    
22. ^ ^{a b} GSM World press release
    
23. ^ Crystal, David (2008-07-05). "2b or not 2b?". Guardian Unlimited. http://books.guardian.co.uk/departments/referenceandlanguages/story/0,,2289259,00.html. Retrieved 2008-07-08.
    
24. ^ ITU Internet Report 2006: digital.life, Chapter 3
    
25. ^ http://www.dslreports.com/shownews/91379
    
26. ^ GSM 03.41, Technical Realization of Short Message Service Cell Broadcast (SMSCB).
    
27. ^ Gil Held: "Data over Wireless Networks". page 105-111, 137-138. Wiley, 2001.
    
28. ^ ^{a b} 3GPP TS 23.038, Alphabets and language-specific information.
    
29. ^ Ian Groves: "Mobile Systems", page 70, 79, 163-166. Chapman & Hall, 1998.
    
30. ^ "t-zones text messaging: send and receive messages with mobile text messaging". T-mobile.com. http://www.t-mobile.com/shop/addons/services/TzonesDetail.aspx?tp=Svc_Tab_TZones&tsp=Svc_Sub_Messaging&tssp=Svc_Sub_TextMessaging&oscid=4CD51BA7-B5AF-4AB2-85E0-50EC0AF141F9. Retrieved 2008-09-18.
    
31. ^ "Support - How do I compose and send a text message to a Sprint or Nextel customer from email?". Support.sprintpcs.com. http://support.sprintpcs.com/doc/sp7648.xml?selectedDeviceId=5707&related=y&Referring%20Related%20DocID%20List%20Index=5&docid=7434&navtypeid=10&pagetypeid=7&prevPageIndex=10. Retrieved 2008-09-18.
    
32. ^ "Answers to FAQs - Verizon Wireless Support". Support.vzw.com. http://support.vzw.com/faqs/Picture%20Messaging/faq_pixmessaging.html#item3. Retrieved 2008-09-18.
    
33. ^ BT trials mobile SMS to voice landline, January 2004, The Register.
    
34. ^ [1], September 2006, SMStextnews
    
35. ^ SMS Tutorial: Introduction to AT Commands, Basic Commands and Extended Commands
    
36. ^ Solutions to the GSM Security Weaknesses,
    Proceedings of the 2nd IEEE International Conference on Next Generation
    Mobile Applications, Services, and Technologies (NGMAST2008),
    pp.576-581, Cardiff, UK, September 2008, PDF
    
37. ^ SSMS - A Secure SMS Messaging Protocol for the M-Payment Systems, Proceedings of the 13th IEEE Symposium on Computers and Communications (ISCC'08), pp. 700-705, July 2008 PDF
    
38. ^ An Analysis of Vulnerabilities in SMS-Capable Cellular Networks: Exploiting Open Functionality in SMS-Capable Cellular Networks (Website)
    
39. ^ An overview on how to stop SMS Spoofing in