Short message service

Short message service

Short Message Service (SMS) is a communications protocol allowing the interchange of short text messages between mobile telephone devices. SMS text messaging is the most widely used data application on the planet, with 2.4 billion active users, or 74% of all mobile phone subscribers sending and receiving text messages on their phones. The SMS technology has facilitated the development and growth of text messaging. The connection between the phenomenon of text messaging and the underlying technology is so great that in parts of the world the term "SMS" is used as a synonym for a text message or the act of sending a text message, even when a different protocol is being used.

SMS as used on modern handsets was originally defined as part of the GSM series of standards in 1985GSM Doc 28/85 "Services and Facilities to be provided in the GSM System" rev2, June 1985] as a means of sending messages of up to 160 characters (including spaces), to and from GSM mobile handsets. [ GSM 03.40] , Technical realization of the Short Message Service (SMS).] Since then, support for the service has expanded to include alternative mobile standards such as ANSI CDMA networks and Digital AMPS, as well as satellite and landline networks.] , Verizon Wireless [cite web|url= |title=Answers to FAQs - Verizon Wireless Support | |date= |accessdate=2008-09-18] and others offer the ability to do this through their websites mail server. For example if you wished to E-Mail a AT&T subscriber whose phone number was 555-555-5555, you would address the message to You are not required to pay to send the message, however the 140 character limit still applies.

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. [ BT trials mobile SMS to voice landline] , January 2004, The Register.]

Short messages can also be used to 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 by far the most common. An alternative way for sending such binary content is EMS messaging which is standardised and not dependent on vendors.

Today, SMS is also used for 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 are slowly being superseded by GPRS services due to their lower overall costsFact|date=May 2008.

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 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). [ SMS Tutorial: Introduction to AT Commands, Basic Commands and Extended Commands] ]

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.

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 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 Centre 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 number, rather than short codes which are usually shared across a lot of brands. Additionally, Long numbers are non-premium inbound numbers.

SMS in satellite phone networks

All commercial Satellite phone networks except ACeS and OptusSat fully support SMSFact|date=May 2008. While early Iridium handsets only support incoming SMS later models can also send them. The price per message varies for the different networks and is usually between 25 and 50 cents per message. 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 a 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. [ [ An Analysis of Vulnerabilities in SMS-Capable Cellular Networks:Exploiting Open Functionality in SMS-Capable Cellular Networks (September 2, 2005)] ] 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.

SMS Spoofing
The GSM industry has identified a number of potential fraud attacks on mobile operators that are caused by abuse of SMS messaging services. The most serious of these 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 100%-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. [ [ An overview on how to stop SMS Spoofing in mobile operator networks (September 9, 2008)] ]

Lack of quality
While sending text messages, the following issues are usuallyFact|date=October 2008 identified:

* lack of timely delivery
* no guaranteed delivery or even reliable notification of delivery
* no possibility of processing a great number of text messages in a short timeframe
* text messages stored on third-party SMSC
* low throughput of text messages

These issues can be solvedDubious|date=October 2008 by introducing SLAs (Service Level Agreement), which a standard agreement of service quality used in the IT world. SLAs guarantee a certain level of services provided to its customers, especially in mission-critical procedures [ [ "TynTec calls for industry benchmarked SMS service level agreements"] Mobile Industry Review (29th April 2008) ] .

See also

* SMS language
* Telegram
* Thumbing


* Short Message Service Centre (SMSC)
* Short message service technical realisation (GSM)
* SMS gateways (sending texts to or from devices other than phones)

Related protocols

* 3rd Generation Partnership Project (3GPP)
* Enhanced Messaging Service (EMS)
* Multimedia Messaging Service (MMS) (a newer standard)
* Short message peer-to-peer protocol (SMPP)
* External Machine Interface (EMI), an extension to the Universal Computer Protocol (UCP)
* WAP Push
* Signaling System 7

Related technology

* BlackBerry
* Instant messaging
* Mobile dating
* Short code


External links

* [ 3GPP] - The organization that maintains the SMS specification.
*PDFlink| [ SMS, the strange duckling of GSM] |101 KiB
* [ ISO Standards (In Zip file format)]
* [ GSM 03.38 to Unicode] - the official GSM 03.38 to Unicode mapping data file

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