You are here: > Documents > SMS > SMS FAQ and Glossary

SMS Frequently Asked Questions

What is SMS?

Short Message Service (SMS) is the ability to send and receive short alphanumeric messages to and from mobile telephones. SMS can also be used as a transport for binary payloads and to implement the WAP stack on top of the SMSC bear. SMS was created as part of the GSM Phase 1 standard.

Why use SMS?

SMS allows users to directly transmit messages to each other without the use of an operator (it is, however, necessary to have the underlying operator controlled wireless service). The first user can send a message to a mobile unit, via a direct connect computer. The SMS protocol of messaging is also "smarter" then standard paging. SMS is a store and forward method therefore, if the end user is not available, the mobile unit is powered off, or the unit is outside a service area, when the unit comes back on line the message will appear. A SMS message can also be sent "certified," where it will notify the message originator of the end user's receipt of the message.

How would you send an SMS Message over the Internet?

The front-end would simply be a section for the message (limit) and a destination address (mobile number). Then, based on your architecture, a lower layer would have to create the correct message based on the request or the message is generate server side. In the case of an end-user sending a message to a mobile unit, it would be a SMS-DELIVER message. Then entire message would then be "encapsulated" in a TCP/IP message and send to the appropriate Short Message Service Centre (SMSC). The MSC would then remove the TCP/IP layer from the message and process the message as if it were generated locally by an operator.

What are some other uses for SMS?

Other uses for SMS are:

  • Voice/Fax Notifications
  • Delivery of Replacement Ringtones, Operator Logos and Group Graphics - Mobile users will select features or options for their phone (ideally from a web site). They enter their mobile number and the feature is sent to their phone via SMS message in a matter of seconds. The user then has the option to select and save or to delete.
  • Unified Messaging - Using a single interface, unified messaging users are able to access all forms of messages (voice mail, email, fax) from a single point.
  • Direct communication - End users can send and receive SMS messages without the use of an operator.

Does SMS support all languages?

SMS is able to support any language, but that language is dependent more on how the handset is configured than anything else. Every region supports different languages and each software build for every phone is different. In the Americas, phones typically support English, Spanish, and Portuguese. In Europe it is vastly different.

What are the two types of SMS?

Point-to-Point and Point-to-Omnipoint (cell broadcast)

What is Point-to-Point?

Point-to-Point uses a dedicated link between the network and the mobile station allowing bidirectional messaging without operator interaction.

What is the maximum length of a Point-to-Point short message?

Two-way data transport = 140 Octet Data Payload Supports Either: 140 bytes for binary data transport (PDU format) 160 characters for text messaging transport (7-bit ASCII).

What are the two types of Point-to-Point messages?

Mobile originated (MO) and Mobile terminated (MT).

What is SM-MT (short message - mobile terminated)?

SM-MT denotes the capability of the GSM system to send a message from the SC to an MS where the message is either received, or, if the recipient device is unavailable, stored for later delivery. A delivery report or failure report is then sent back to the SC. These messages may be input to the Service center by other mobile users (via a mobile originated short message) or by a variety of other sources, e.g. speech, telex, or facsimile.

What is SM-MO (short message - mobile originated)?

SM-MO denotes the capability of the GSM system to send a message from an M to an SME via an SC and to provide information to the MS about the delivery or failure of that message. These messages may be destined for other mobile users, or for subscribers on a fixed network.

What are the specific types of Point-to-Point messages?

  • SMS-DELIVER - Sending a short message from the SC to the MS.
  • SMS-DELIVER-REPORT - Replying with an error cause.
  • SMS-SUBMIT - Sending a short message from the MS to the SC.
  • SMS-SUBMIT-REPORT - Reply with an error cause.
  • SMS-STATUS-REPORT - Sending a status report from the SC to the MS.
  • SMS-COMMAND - Sending a command from the MS to the SC.

What is Point-to-Omnipoint?

Point-to-Omnipoint, or Cell Broadcast, sends messages to predetermined cell broadcast areas. Unlike Point-to-Point messaging, Cell Broadcast does not use a dedicated link. The network operator is where all messages originate and the recipients include all users within a given cell, area, or network. Also unlike Point-to-Point, CB messages do not provide any assurance that the message was recieved.

What is the maximum length of a Point-to-Omnipoint short message?

A Point-to-Omnipoint short message is a maximum of 93 charaters (82 octets) in length.

Where is it determined which MSs will receive which CB messages?

At the origination and termination points. At the origination point, the sender (or network operator) broadcasts messages on certain "channels". The sender indicates the frequency and duration of transmission. At the termination point, the user selects which "channels" will be displayed on his mobile station. If the MS is switched on and idle, it is able to identify and ignore re-broadcasts of messages that have already been received.

How do mobiles know to display only those messages desired by the MS user?

CB messages are assigned message classes that categorize the type of information contained in the message.

What are the error conditions that can return to an SC from an MS?

  • Unknown subscriber - Message is rejected because there is no directory number for the mobile subscriber (GSM 09.02).
  • Teleservice not provisioned - Message is rejected because the recipient MS has no SMS subscription (GSM 09.02).
  • Call barred - Message is rejected due to barring of the MS (see GSM 09.02, description of the Barring supplementary service, GSM 02.04 and 03.11, and description of Operator Determined Barring, GSM 02.41 and 03.15).
  • Facility not supported - The message is rejected due to no provision of the SMS in the VPLMN (GSM 09.02).
  • Absent subscriber - The message is rejected because there was no paging response (GSM 04.08), the IMSI record is marked detached (GSM 09.02), or the MS is subject to roaming restrictions (GSM 09.02).
  • MS busy for MT SMS: The message is rejected because of congestion encountered at the visited MSC.
  • SMS lower layers capabilities not provisioned - Message rejected due to MS not being able to support the SMS. The short message transfer attempt is rejected either due to information contained in the class-mark, or the MSC not being able to establish connection at SAPI (GSM 04.08 and 09.02).
  • Error in MS: message rejected due to an error occurring within the MS at reception of a short message (lack of memory or protocol error).
  • Illegal subscriber - Message rejected because of failed authentication.
  • Illegal equipment - Message rejected because the MS was black-listed.
  • System failure - Message rejected due to network or protocol failure.
  • Memory capacity exceeded - Message rejected because the MS doesn't have enough memory.

How can SMS be used to program phones?

Nokia has created a new protocol called Smart Messages which sends configuration messages to mobile phone units with header definitions stating that the message is a configuration message. These Smart Messages make use of the SMS protocol.

What are the classes of SM-MT (mobile terminated) messages?

Classes identify the message's importance as well as the location where it should be stored. There are 4 message classes.

  • Class 0 - Indicates that this message is to be displayed on the MS immediately and a message delivery report is to be sent back to the SC. The message does not have to be saved in the MS or on the SIM card (unless selected to do so by the mobile user).
  • Class 1 - Indicates that this message is to be stored in the MS memory or the SIM card (depending on memory availability).
  • Class 2 - This message class is Phase 2 specific and carries SIM card data. The SIM card data must be successfully transferred prior to sending acknowledgement to the SC. An error message will be sent to the SC if this transmission is not possible.
  • Class 3 - Indicates that this message will be forwarded from the receiving entity to an external device. The delivery acknowledgement will be sent to the SC regardless of whether or not the message was forwarded to the external device.

Glossary of SMS/GSM related terms

Air Interface
The standard operating system of a wireless network. Air interface technologies include: AMPS, TDMA, CDMA and GSM.
AMPS- (Advanced Mobile Phone Service)
An analog cellular radio standard that serves as the foundation for the U.S. cellular industry. AMPS represents the first generation of wireless networks.
The traditional method of modulating radio signals. Most U.S. cellular phones use analog but are migrating to digital technologies. AM (amplitude modulation) and FM (frequency modulation) are the two most common methods of analog modulation.
API- (Application Program Interface)
A language and message format used by an application program to communicate with the operating system or some other system or control program such as a database management system (DBMS) or communications protocol. APIs are implemented by writing function calls in the program, which provide the linkage to the required subroutine for execution. Thus, an API implies that a program module is available in the computer to perform the operation or that it must be linked into the existing program to perform the tasks.
ASP- (Application Service Provider)
An organization that hosts software applications on its own servers within its own facilities. Customers access the application via private lines or the Internet. ASP is also called a "commercial service provider."
CDMA- (Code Division Multiple Access)
An air interface technology that was developed by the U.S. military and commercialized by the U.S. company Qualcomm. CDMA supports SMS with a message length of 120 characters. With CDMA, each conversation is digitized and then tagged with a code. The mobile phone receives a signal to locate that particular code and it then deciphers the conversation off the airwaves. It codes each conversation expanding it 128 times, making it easy to decipher at the receiving end.
3G CDMA evolution from cdmaONE supported by cdmaONE operators. Phase 1 provides 144 Kbps data rate and Phase 2 up to 2 Mbps. See Third Generation.
The name used by the CDMA Development Group (CDG) for CDMA networks (IS-95) using 2nd-generation digital technology.
CDPD- (Cellular Digital Packet Data)
An enhanced packet overlay on analog cell phone networks used to transmit and receive data. This technology allows data files to be broken into a number of packets and sent along idle channels of existing cellular voice networks. CDPD provides 19.2 Kbps and is deployed by AT&T among several other carriers.
Refers to the region within which a paging receiver can reliably receive the transmission of the paging signals.
A digital signal is composed of electrical pulses representing either zero or one. Because digital signals are made up only of binary streams, less information is needed to transmit a message. Digital encoding therefore increases the capacity of a given radio frequency. Furthermore, only digitized information can be transported through a noisy channel without degradation. Even if corruption occurs, as long as the one zero pattern is recognizable, the original information content can be perfectly replicated at the receiving end.
GPRS- (General Packet Radio Service)
Allows information to be sent and received across a mobile telephone network that makes Internet connections easier. GPRS is used to boost wireless data transmission over GSM networks. GPRS can achieve 171.2 kilobits per second (kbps), which is about three times as fast as the data transmission speeds possible over today's fixed telecommunications networks and ten times as fast as current GSM networks. Unlike existing digital wireless Net connections, no dial-up modem is necessary.
GSM- (Global System for Mobile Communications)
A digital mobile phone standard used extensively in Europe, the Middle East, Africa, Asia and in parts of America and Canada. First introduced in 1991, the GSM standard has been deployed at three different frequency bands: 900 MHz, 1800 MHz and 1900 MHz. GSM 1900 is primarily deployed in North America. Named after its frequency band around 900 MHz, GSM-900 has provided the basis for several other networks using GSM technology. GSM uses narrowband TDMA which allows eight simultaneous calls on the same radio frequency. Along with CDMA and TDMA it represents the second generation of wireless networks.
HDML- (Handheld Device Markup Language)
A specialized version of HTML designed to enable wireless pagers, cell phones and other handheld devices to obtain information from Web pages. HDML was developed by (formerly Unwired Planet) before the WAP specification was standardized. It is a subset of WAP with some features, not included in WAP. AT&T Wireless launched the first HDML-based service in 1996.
NTT DoCoMo's mobile Internet access, launched in February 1999. I-mode is an alternative to WAP, though it is only implemented in Japan. It offers Internet access and email service. While WAP uses HDML, I-mode relies on Compact HTML (C-HTML). Both languages are a simple version of HTML, for use on mobile phones. Today more than 7000 sites are I-mode compatible and offer a wide range of services over mobile phones: mobile banking, ticket reservation, cartoons downloading, etc.
IDEN- (Integrated Digital Enhanced Network)
A wireless communications technology from Motorola that provides support for voice, data, short messages (SMS) and dispatch radio (two-way radio) in one phone. Operating in the 800MHz and 1.5GHz bands and based on TDMA, iDEN uses Motorola's VSELP (Vector Sum Excited Linear Predictors) vocoder for voice compression and QAM modulation to deliver 64 Kbps over a 25KHz channel. Each 25KHz channel can be divided six times to transmit any mix of voice, data, dispatch or text message. Used by various carriers around the globe, Nextel Communications provides nationwide coverage in the U.S.
Messaging Gateway
A computer system that converts one messaging protocol to another. It provides an interface between two store and forward nodes, or message transfer agents (MTAs).
Data that describes other data. The term refers to any file or database that holds information about another database's structure, attributes, processing or changes. Metadata surrounding the Simplewire service and wireless device data includes whether a mobile device is turned on or off, the geographic location, routing commands, screen size, the amount of characters a particular phone can receive, character support, two-way capabilities and any other phone features.
One-Way Text-Messaging
Sending short (wireless data) messages to a smart phone, pager, wireless PDA or other handheld device via the Internet. Text-messaging implies sending short messages generally no more than a couple of hundred characters in length. In Europe, text-messaging was popularized by the GSM cell phone system's Short Messaging Service (SMS), which supports messages of up to 160 characters.
PCS- (Personal Communication Services)
A second-generation digital voice, messaging and data cell phone system in the 2GHz range. PCS is supported mostly by GSM.
PDC- (Personal Digital Communications)
A Japanese digital cellular standard that supports SMS.
SIM Card
Smart card that gives GSM phones their user identity. SIM cards make it easy for phones to be rented or borrowed.
Smart Phone
A digital cellular phone that has text-messaging, web access and other data services along with voice.
SMS- (Short Message Service)
The transmission of short text-messages to and from a mobile phone, fax machine and/or IP address. Messages must be no longer than 160 alphanumeric characters and contain no images or graphics. Once a message is sent, it is received by a Short Message Service Center (SMSC), which must then get it to the appropriate mobile device. To do this, the SMSC sends a SMS Request to the home location register (HLR) to find the roaming customer. Once the HLR receives the request, it will respond to the SMSC with the subscriber's metadata: 1) inactive or active 2) where subscriber is roaming. If the response is 'inactive' then the SMSC will hold onto the message for a period of time. When the subscriber accesses the device the HLR sends a SMS notification to the SMSC, and the SMSC will attempt delivery. The SMSC transfers the message in a Short Message Delivery Point-to- Point format to the serving system. The system pages the device, and if it responds, the message gets delivered and receives verification.
SMSC- (Short Message Service Center)
The hardware device submitting the messages. Currently, SMSC devices support binary formats. A software module called the SMS gateway is used to give instructions to the SMSC. The protocol described in this draft is proposed to provide a standard for service providers to interact with SMS gateways or SMS centers.
SNPP- (Simple Network Paging Protocol)
A sequence of commands and replies where pages are delivered to individual paging terminals. The most obvious benefit is the elimination of the need for modems and phone lines to produce alphanumeric pages, and the ease of delivery of pages to terminals in other cities or countries.
TAP- (Telocator Alphanumeric Protocol)
An SMS standard. The pre-cursor to TDP, a simple protocol dedicated to the forwarding of alphanumeric pages. Although the features and capabilities of TAP are in TDP, the TAP protocol may co-exist with TDP. The TAP protocol may be utilized to forward binary data to RF linked computers if input is formatted and processed.
TDMA- (Time Division Multiple Access)
A method of digital wireless communications transmission allowing a large number of users to access a single radio-frequency channel without interference. Each user is given a unique time slot within each channel. SMS Mobile Originate has now gone live on several TDMA networks around the world including Telecom New Zealand, Midwest Wireless USA, Algar Telecom Brazil and Cellcom Israel. Other TDMA network operators such as AT&T Wireless in the U.S. have launched SMS MO nationally.
TDP/TME- (Telocator Data Protocol)
A suite of protocols used for sending messages from a computer, through a paging system, to a mobile receiving computer. Together, these protocols define the flow of messages from input devices through several processing steps until the entire message is received by an RF linked computer. The set is compromised of several protocols including TME, TRT and TMC.
See One-Way Text-Messaging and Two-Way Text-Messaging
Third-Generation - (3G)
A new wireless standard promising increased capacity and high-speed data applications up to two megabits. Implemented in Europe as UMTS and cdma2000 in North America. Goals are high-quality multimedia and advanced global roaming (in house, cellular, satellite, etc.).
TNPP- (Telocator Network Paging Protocol)
A one-way paging networking standard. TNPP is supported by most one-way and two-way messaging networks, but can only be used for one-way messaging. The TNPP protocol is used for moving pages from one paging system to another over standard lines.
Two-Way Text-Messaging
Sending short (wireless data) messages to a smart phone, pager, PDA or other handheld device from another web enabled device. Two-way implies that the device receiving the message is able to reply via text-messaging as well. Text-messaging implies sending short messages generally no more than a couple of hundred characters in length. In Europe, text-messaging was popularized by the GSM cell phone system's Short Messaging Service (SMS), which supports messages of up to 160 characters.
VPN- (Virtual Private Network)
Private networks that are configured within a public network. Carriers build VPNs that appear as private national or international networks to the customer, but physically share backbone trunks with other customers. VPNs enjoy the security of a private network via access control and encryption, while taking advantage of the economies of scale and built-in management facilities of large public networks. VPNs have been built over X.25, Switched 56, frame relay and ATM technologies. The VPN adds an extra layer of security. A huge growth in VPN use is expected.
WAE- (Wireless Application Environment)
The part of the WAP protocol that application and service developers use most in their work. The WAE consists of the WML and WMLScript specs as well as the Wireless Telephony Application Interface (WTAI) that specifies how WAP applications can access mobile phone functionality (initiate a call, send an SMS).
WAP Alert
An exclusive Simplewire product that enables wireless devices to receive a reroute via text-message to a url where the user can access more information than can be provided within the character limit of a text-message.
WAP Stack
A set of protocols that covers the whole process of wireless content delivery: From the definition of WML and WML Script for creating the actual layout of the content to the specifications of security measures in the WTLS, and to the lowest parts of the stack dealing with the actual transport of content.
WAP- (Wireless Application Protocol)
An open standard for communication between handsets and the Internet. WAP is a wireless communications environment for delivering Web data to wireless terminals with minimal screen display. An initiative started by Unwired Planet, Motorola, Nokia and Ericsson to develop a standard for wireless content delivery on the next generation of mobile communicators. WAP strips all but graphics for display on small screens, such as mobile phones. A mini-browser is an integral part of WAP enabled phones. WAP enabled phones first appeared in Europe at the end of 1999.
WCTP- (Wireless Communication Transfer Protocol)
A protocol that transfers content between wireline and wireless devices. The protocol may operate over any desired transport protocol that is block oriented. The protocol itself deliberately does not address the issues of security or authentication of transactions in a highly secure manner.
WIM- (Wireless Instant Messaging)
Bridges the gap between wired and wireless networks. WIM seamlessly allows a desktop user to instantly send a message to a handset.
WIN - (Wireless Intelligent Network)
Transaction processing infrastructure for wireless systems.
Wireless Bridge
A device used to transmit and receive radio frequencies over the air between two LANs.
Wireless LAN
A local area network that uses radio frequency transmission over the air. Works like a cellular phone system with roaming between cells.
Wireless Modem
Modem and antenna for analog and digital cellphones, CDPD, ARDIS, BellSouth Intelligent Wireless Network, etc.
Wireless Portal
A Web site that supports users with smart phones or alphanumeric pagers.
WMF- (Wireless Message Format)
A standard format for presenting data received through a paging system to mobile computers. The application at the MED uses this format to encode binary data and control information sent to a remote device. This information is received completely intact by the MCD.
WML/WMLScript- (Wireless Markup Language/Script)
The languages used to create WAP pages. WML is similar to the way HTML is used to create web pages and WMLScript is based on JavaScript. Both are adapted and optimized for a wireless environment (compression to save bandwidth).
WMP- (Wireless Message Protocol) Server
Simplewire's very own WMP server allows the Wireless Message Gateway to accept all requests regardless of carrier, intelligently translate the information into the correct wireless protocol and route the information to the correct wireless carrier. Simplewire's WMP server is able to provide subscribers with a consistent and simple interface via the Internet to any wireless device. The WMP Server is Simplewire's core technology and includes four layers of the text-messaging network. They are the Acceptance and Delivery Layer, the Processing Layer, the Consolidation Layer and the Carrier Routing Layer.
WSP- (Wireless Service Provider)
Any organization that delivers wireless services to its customers.
WTLS- (Wireless Transport Layer Security)
The security layer of the WAP which provides privacy, data integrity and authentication for WAP services. WTLS, designed specifically for the wireless environment, is needed for the client and server to be authenticated in order for wireless transactions to remain secure and also because the connection needs to be encrypted. For example, a user making a transaction with a bank over a wireless device needs to know that the connection is secure and private and not subject to a security breach during transfer. WTLS is needed because mobile networks do not provide complete end-to-end security.