Find out the meaning of common terms and jargon you'll find used in the mobile industry, as well as some specific terms used by OpenMarket.

Z  Numbers & Symbols



Application to Person. OpenMarket is a provider of A2P SMS and MMS messaging solutions. We enable enterprises and businesses to communicate with their end users using applications like:

  • Customer-built platforms (connected via our APIs)
  • Web-based solutions such as our Mobile Engagement Platform (MEP)
  • Custom solutions built by our Professional Services team

We offer solutions for both messaging directions; e.g. Application to Person, and Person to Application (P2A).

alpha-2 codes

A two-letter code that identifies a country or region, as defined by ISO 3166-1. For example, AU is Australia and CA is Canada. You can find a list of the codes on Wikipedia.

alpha sender ID

This is another term for an alphanumeric message originator. These use letters (or other characters such as the underscore), and is therefore not a dialable number.


Application Programming Interface. APIs enable software systems to connect to one another. OpenMarket offers APIs so that your developers can connect your own platform to ours.


Application Service Provider. A business that offers applications you must reach over a network, typically the Internet (e.g. cloud computing). OpenMarket is a type of ASP specializing in mobile messaging. As we are in the mobile industry, we refer to ourselves as a mobile messaging solutions provider.

We also partner with specialist ASPs that can further enhance your mobile messaging; for example one of our partners offers speech and natural language technology solutions. To find out more, see Partner Solutions.

A synonym of this term is "Application Provider".


A preconfigured message that is sent in response to an MO message sent by an end user. As an example, if an end user texts STOP, the receiving system may respond with a text message confirming the end user's action: "Thank you. We received your request and will no longer send you messages."



Business to Consumer. Any business model or transaction where the business is interacting with individual consumers rather than with another business.

A synonym of this term is E2P or Enterprise to Person.

batch import

This term is sometimes used in the industry to refer to broadcasting. At OpenMarket, we would only use this term in the context of uploading data into an application such as MEP, but not to refer to broadcast messaging to end users.

binary SMS

Binary SMS messages enable you to send other forms of data, rather than a normal text SMS message. These are commonly used for "over the air" installation messages or other information to a specific port or application on the end user's mobile phone. Our SMS messaging API fully supports sending binary messages; see Example Text, WAP Push and Binary Messages.


A software application that runs automatic tasks which simplify interactions within RCS. An example of a bot is a chatbot.

broadcast message

Broadcast message refers to sending the same message to multiple end users using either SMS or MMS. With OpenMarket MEP you can personalize broadcast MMS messages, as well as spread messages through time and receive replies back. For information see, Broadcasts Overview.


Broadcasting refers to performing the same action for multiple end users. Broadcasting is one of the core features of OpenMarket MEP. You can broadcast SMS messages, MMS messages, and trigger a service for any number of end users. For information see, Broadcasts Overview.

bulk messaging (or bulk SMS)

Bulk messaging is used in the industry to mean one of two things:

  • Sending the same message to multiple end users at the same time. This term is sometimes viewed negatively as it is linked to disreputable businesses "spamming" end users with messages.
  • The pricing for SMS messaging outside of the US and Canada. Bulk SMS is free for a mobile phone user to receive, with the sender paying the total cost of messages. This is in comparison to premium rate SMS and standard rate SMS (in the US and Canada).

Because of the multiple meanings and negative connotation, we do not use this term in our documentation. Note that if you are sending the same message to multiple end users we refer to this as broadcasting (or broadcast message).



A North American term for a mobile operator.

carrier lookup

A North American term for a mobile operator lookup.


Code Division Multiple Access . A method for sending and receiving information wirelessly, such as over radio frequencies. CDMA allows for several transmitters (e.g. mobile phones) to use the same frequency bandwidth (or "spread").

Variants of CDMA are used by mobile operators to send and receive calls, texts and other data with their end users, and the acronym CDMA is used to collectively refer to its use as a technology standard. It is common in the US, Russia, and some parts of Asia and Africa.

Currently, CDMA is one of two dominant standards used globally, the other being Global System for Mobile Communications (GSM). Most phones only support one of these technologies, and so end users moving between regions may not be able to use their phones on a competing mobile operator's network. Both standards may eventually be replaced by LTE, a new standard based on GSM.

character encoding

The way in which letters, numbers, spaces and symbols are represented in an abstract way. For example, Morse code is a type of character encoding. Software, including that on a mobile phone, requires character encoding so that it can store, retrieve and send text to other systems.

When you send an SMS message via OpenMarket, your message request just needs to use UTF-8 character encoding. We ensure that the message is sent using the best available character encoding for that mobile operator and region.

Related terms are "data encoding" and "character sets".


A type of artificial intelligence system that conducts a conversation using sound or text. Such systems are often designed to simulate, as naturally as possible. Chatbots are integrated with RCS messaging.

chip list

In an RCS message, a chip list consists of clickable elements in the message that represent steps or actions an end user takes. As an example, an RCS message might enable the end user to purchase concert tickets, and the steps could include viewing prices, choosing seats, entering payment information, and accessing the mobile tickets. Chips are also known as 'action buttons'.

cloud messaging provider

Another term for a mobile messaging solutions provider.

concatenated message

A mobile message that requires more than one SMS to send. Also known as a multipart message. The message is deconstructed into parts and then reconstructed on the mobile phone so that the end user sees one long message. This gets around the byte size limitation of SMS (which limits the number of characters you can send in an SMS). For more information, see Single and Multipart Messages.

concatenated SMS

Another term for a multipart message.

Coordinated Universal Time

See UTC.

country code

The telephone dialing prefix required so that you can reach a phone number outside your own country or region. For example, 1 is the country code for US and Canadian numbers, 44 for UK numbers, and 371 for Latvian numbers.

Synonyms include "dialing code", "country calling code" and "country dial in codes".


Common Short Code. A term used in the US and Canada for short codes that work across multiple mobile operators. These are sometimes referred to as "inter-operator" codes.

The reason why a "common" short code is required is that short codes are not regional in the same way as regular mobile numbers (or other phone numbers). Short codes are uniquely provisioned in each mobile operator's systems; so, for example, if you want Verizon end users to send you messages, you need to provision the short code within the Verizon system. Without this system of common short codes, the same code could conceptually end up provisioned to different businesses with each mobile operator.

Most regions that allow short codes have a provisioning system in place to ensure codes are accessible across all (or most) operators. In the European Union there are even EU-wide short codes.


Common Short Code Administration. A US organization that administers short codes. Your OpenMarket account manager can help you with leasing a short code from the CSCA.


Cellular Telecommunications & Internet Association. A US-based organization that represents wireless communications internationally, particularly mobile communication and devices. The association's members include mobile network operators, aggregators, and manufacturers. It advocates to governments on behalf of members and creates industry guidelines.


deactivated numbers

A phone number that a mobile operator has taken out of service for an end user, either because the end user has switched operators or has closed their account.

In the US, it is important that you do not message a phone number that has been deactivated, as numbers can be assigned to new users within 2 days. For more information, see Handling Deactivated Phone Numbers.

deactivation reports

Reports issued by certain mobile operators containing information about recently deactivated numbers in the US. OpenMarket receives and passes on these reports so that you can keep your records up to date and to help you avoid inadvertently sending messages to phone numbers that are no longer opted in to your programs.

For more information, see Handling Deactivated Phone Numbers.

dedicated short code

A short code that is leased and used by only one business. All traffic sent to the code is received by that business, and there is no requirement for a keyword that routes to just that business. In comparison, a shared short code refers to a code used by multiple businesses, with traffic separated via keywords.

delivery receipts (DLRs or DRs)

Information provided by a mobile operator about whether a message was delivered to a mobile phone number. If there was an issue reaching the number, then the delivery receipt will normally indicate the type of issue.

A synonym for delivery receipts is "delivery reports".

dialing code

A synonym for country code.

direct connection

A contractually bound technical connection between OpenMarket and a mobile operator that gives OpenMarket a direct technical connection to the operator's messaging center (SMSC). This means that any traffic is delivered from that SMSC directly to the mobile phone of the subscriber. This traffic can be either on-net, where the recipient is one of the operator's subscribers, or off-net, where the recipient is in the same country but subscribed via another operator.

OpenMarket has a large number of direct connections globally. We focus on maintaining strong relationships with key mobile operators, from which we receive excellent support and pricing. Where we are not directly connected, we use high-quality routes to ensure the best delivery performance.



Enterprise to Person. This refers to any business models or transactions where the enterprise is interacting with individual consumers rather than with another business.

A synonym is B2C or Business to Consumer.

end user

The people — such as your customers or employees — with whom you are sending and receiving mobile messages.


External Short Messaging Entity. The ESME receives a message from a customer. A connection is established with an SMSC, and then that message forwarded on to the SMSC for delivery to a destination recipient. You are an ESME.

expression language

Expression language (EL) is a MEP scripting language that enables you to perform a wide range of complex operations. The most common task of EL is to create and update dynamic values, often as part of a service. Simple uses of EL, used by many services, include storing an end user's details (e.g. name, age, and address) and counting the number of times the service has been triggered.

For more information, see Overview of Expression Language.



Frequency Division Multiple Access. A method for sending and receiving information wirelessly, such as over radio frequencies. When using FDMA, the mobile phone and the cell tower use separate radio frequencies so that they can both receive and transmit simultaneously. For example, one phone call uses two of the available frequencies with the cell tower, two simultaneous phone calls uses four frequencies, and so on.

Related technologies are CDMA and TDMA.


Free to End User. A term used in the US and Canada to refer to messages that are free for the end user to receive. This is because, in the US and Canada, end users are charged to both send and receive messages unless their account includes unlimited SMS.

Senders of a FTEU message pay two charges; the sending charge and the receiving charge.

In other regions, both landline and short code FTEU numbers exists; however, these refer to numbers where the end user isn't charged to call or text the number.


gateway (GW)

A connection that bridges two different networks. OpenMarket messaging APIs act as gateways between your platform and the mobile operators.

Global System for Mobile Communications (GSM)

A technology standard used by mobile operators to send and receive calls, texts and other data with end users. It uses TDMA as the underlying technology to send and receive radio frequencies. GSM is common in Europe, South America, Africa, Asia, and Australasia.

Currently, GSM is one of two dominant standards used globally, the other being Code Division Multiple Access (CDMA). Most phones only support one of these technologies, and so end users moving between countries or changing networks may not be able to use their phones to a competing mobile operator.

grey routes

A messaging route (typically international) that avoids paying the mobile operators their inter-networking fees. It is referred to as "grey" because the route is legal (does not break any laws or contracts) but is still unwanted in the destination network. Grey routes are cheap but often unreliable.

OpenMarket uses only direct connections and high-quality routes. For information about avoiding grey routes, see the OpenMarket blog.


high-quality route (HQ Route)

A connection where there is a hop between OpenMarket and a direct connection. The hop is provided by a regional aggregator or dominant operator that can supply a direct connection to the desired market or region.

OpenMarket maintains both redundant high-quality routes and direct connections, so that if a route experiences an outage we can continue to send and receive messages.


Home Location Register. The database that each mobile operator maintains of its end users (mobile subscribers). The database includes information about the services provisioned for each end user (such as data services) and their current location. The HLR includes an entry for every SIM card that the mobile operator has issued and whether a number they originally provided has been ported to another operator.

HLR lookup

A lookup operation that retrieves information about an end user from the mobile operator's HLR.


The term hops, such as "one hop" or "two hops" refers to how many connections are between a mobile aggregator and the specific operator in the destination country. For example, if aggregator "M" wishes to send a message to a user on Vodafone Australia, they may be connected to:

  • Vodafone Australia via an on-net direct connection (which is referred to as zero hop)
  • Another Australian operator, which is an off-net direct connection (also referred to as zero hop)
  • An aggregator or non-Australian operator with a direct connection to Vodafone Australia (one hop)
  • An aggregator or operator that has a connection to a directly connected aggregator or operator (two hops)

A similar, more fun version of this is "Six degrees of Kevin Bacon".


Hypertext Transfer Protocol. It is the most common standard for transmitting information over the Internet.

A more secure protocol for transmitting information is HTTPS, which uses SSL to protect the HTTP connection. We recommend that you always connect to OpenMarket using HTTPS.



International Mobile Subscriber Identity. This is a unique number stored on the SIM card (or in some cases, the mobile phone) to identify the end user and their mobile operator. Mobile operators use the IMSI and mobile phone number to track and connect to the right mobile phone.


Internet of Things. It refers to connecting physical objects to the Internet so that the objects can provide data. The data might be the current state of the object (e.g. an alarm is either on or off) or the state of something related to the object (e.g. there is no milk in the fridge).

SMS and MMS messaging play a part in IOT solutions, because they can provide connectivity in places or scenarios where a direct data connection is not suitable.



JavaScript Object Notation. JSON is a lightweight format used to send data between two systems. It was designed to be easy for developers to read and write, and for machines to parse and create. It is also language independent, which means that the systems exchanging data do not need to use the same programming language (such as C++).

OpenMarket SMS, MMS and RCS APIs accept JSON-formatted requests.



A short word (or string of characters) that an end user must send in an MO SMS to interact with a specific messaging campaign. Traditionally, keywords were associated with short code marketing campaigns, but campaigns using any type of two-way message originator can make use of keywords. A two-way originator will normally have multiple associated keywords to respond to different user requests.

Some keywords like HELP and STOP are required in certain regions. A business may use many keywords so that they can respond to a variety of end user messages with specific answers or message flows. For example, a hotel might use "pool", "fitness", and "room service", and return a separate response for each keyword.

Keywords normally occur at the beginning of a text message. However, if you’re using MEP to route messages, the keyword can be in any part of the message; for example, you could look for the word "bingo" in any part of the message if you want to distinguish between bingo enthusiasts and the rest of the world.



The time between when a message is submitted to a mobile aggregator to when it is received by a mobile phone. Typically message latency is a few seconds. OpenMarket can offer extremely low latency messaging because of our excellent network connections, highly available systems, and ability to handle large message volumes.

Other factors affecting latency include whether the receiving mobile phone is switched off and the availability of the mobile network. These and other factors can extend message latency to minutes, hours or days.

Latency is also used to describe the speed at which delivery receipts are sent.

least cost routing (LCR)

OpenMarket does not offer or use least cost routes.

Least cost routing refers to using the cheapest possible route to send a message. This type of routing would regularly make use of grey or other unreliable routes, as well as often using multiple hops to reach the destination.

long code (or long number)

Another term for VMN.

long message

Another term for a multipart message.


Long Term Evolution. A technology standard used by mobile operators to send and receive calls, texts and other data with their end users. Currently it is common in South Korea and is becoming popular in places such as Sweden, Japan, Australia, and the US. It is based on GSM, and may eventually replace the two main technology standards of GSM and CDMA.



Messaging-as-a-Platform. An advanced messaging platform that provides a richer messaging experience with the integration of chatbots and other types of bots. Google is an example of a MaaP provider.

MCC/MNC tuple

The mobile country code (MCC) and mobile network code (MNC) together identify each mobile operator. The codes are used across the mobile industry (including by OpenMarket), to ensure that messages and calls are routed to the appropriate mobile operator.


Mobile Engagement Platform. An OpenMarket messaging platform that enables customers to create and deploy messaging programs using either a GUI or APIs. MEP supports a wide variety of use cases, including both one-way and two-way messaging.

One of the most distinctive features of MEP is a drag-and-drop GUI that lets you quickly design both simple and complex services, and associate them with configurable contact lists, routes, and keywords.

To find out more about MEP, see our MEP Videos.

message originator

Refers to the address from which you send (and receive) messages. A message originator can be one of the following types:

  • Short codes
  • Virtual mobile numbers (VMNs), also known as long codes
  • Toll-free numbers (US/Canada only)
  • Landline numbers (US/Canada only)
  • Alphanumeric strings

We use this term to specifically mean only your own numbers, and never an end user's phone number.

For more information, including which originators are available in key regions, see Message originators.

mobile aggregator

A business that provides a technical connection between mobile operators and businesses. OpenMarket acts as mobile aggregator; however, because we offer additional services and solutions above and beyond being an aggregator we refer to ourselves as a mobile messaging solutions provider.

Mobile Crediting

An OpenMarket API that enables you to offer monetary credit to pre- and post-pay end users on any UK mobile operator. The amount is added to a pre-pay end user's balance or applied to a contract end user's monthly bill.

We offer Mobile Crediting through both MEP and our APIs (see Mobile Crediting Overview).


A method for sending and receiving MMS messages. MM7 was developed as an industry standard by 3GPP and uses SOAP with attachments, transported via HTTP.

OpenMarket offers both an MM7 API and a JSON API for sending MMS messages.


Multimedia Messaging Service. MMS messages can include multimedia content and, depending on the mobile operator, can be much larger than SMS messages in data size. For more information, see Before You Begin.


Mobile Marketing Association. An international trade organization that represents mobile communications, particularly in mobile marketing. The association's members include large enterprises, marketing agencies, aggregators, media firms, and mobile operators. Its aim is to grow mobile marketing and the related technologies. Additionally, MMA committees are involved in creating industry best practices and standards.

mobile messaging solutions provider

A business that offers mobile messaging solutions and mobile aggregation services. OpenMarket is a mobile messaging solution provider.

mobile network operator (MNO)

A mobile operator that owns or controls all the physical infrastructure (such as cell towers) and radio spectrum allocation required to provide mobile services.

An MNO may sell access to its network to a MVNO.

mobile number portability (MNP)

A capability offered by mobile operators that enables end users to keep their phone number when switching from one mobile operator to another. It is supported in most (but not all) countries, with some differences in implementation:

  • In the majority of MNP-enabled countries, the mobile operators share a central database of ported numbers. This is a European and International best practice.
  • In the UK, calls and messages are still routed to the original mobile operator, which then routes the call or message. If an end user moves to a third operator, then the original mobile operator routes to the new operator.

Mobile operators can also perform an HLR lookup for messages or calls to international destinations.

Where MNP is supported, OpenMarket can route the message to the correct mobile operator.

mobile operator

The term used by OpenMarket to generically refer to both mobile network operators and mobile virtual network operators.

In some situations, it may also include the suppliers of high-quality routes to mobile operators; for example, when talking about receiving delivery receipts from operators. We do this where readability is more important and there is no technical difference that is useful for you to know between the mobile operators and the suppliers.

mobile operator lookup

A lookup operation that determines the mobile operator associated with a particular mobile phone number. The lookup can also return information about the capabilities and location of the operator.

Synonyms include "carrier lookup" and "network lookup".

mobile originated (MO)

Mobile messages sent from an end user to your business. This phrase refers to a mobile phone as the sender (originator) of a message.

mobile phone

An extremely sophisticated radio transmitter/receiver that, in newer models, can efficiently catch Pokémon.

mobile terminated (MT)

Mobile messages sent from your business to an end user. This phrase refers to a mobile phone as the receiver of a message.


Mobile Station International Subscriber Directory Number. This is a mobile phone number of an end user, including the country code. This, along with the IMSI, is what the mobile operators use to track and connect to the right mobile phone.

multipart message

A mobile message that requires more than one SMS to send. Also known as a concatenated message. The message is deconstructed into parts and then reconstructed on the mobile phone so that the end user sees one long message. This gets around the byte size limitation of SMS (which limits the number of characters you can send in an SMS). For more information, see Single and Multipart Messages.

Synonyms are "long message" and "concatenated message".


Mobile Virtual Network Operator. A mobile operator that does not own any physical wireless infrastructure, such as cell towers, but instead provides services by purchasing bulk access of another operator's services.



North American Number Plan. The NANP refers to the telephone number plan used for 20 primarily North American countries. The plan has 25 distinct regions. The international country code "1" routes to phone numbers in the NANP. Within the plan, the numbers are 10 digits long, with the first three digits used for the area code. The combined format is:


where N is restricted to digits between 2 to 9.


North American Number Plan Administration. NANPA administers the numbering plan areas for the US, Canada, and some Caribbean countries; essentially any country that use a country code beginning with "1". NANPA ensures that numbering resources are distributed neutrally and helps to coordinate numbering area codes. The individual countries each have their own regulatory bodies (or a dominant telephony network) that work with NANPA to distribute numbering resources in their own regions.

non-geographic telephone numbers

This is a term used by the UK telecoms industry to refer to UK numbers available that are not linked to a geographic region. There are three options used by businesses:

  • Freephone numbers — where the business pays all costs, regardless of whether the caller is on a mobile phone, landline or payphone.
  • 03 numbers — where the caller is billed the same as they would for a local call
  • Service / Premium numbers — where the caller is charged twice: by the business, and by their mobile operator (or telephone company)

numeric sender ID

This is another term for a message originator that is a number (e.g. a long code, VMN, or short code).



Originating Address. A synonym for message originator.


Sending a message via a mobile operator that is not directly associated with the mobile phone number. This is an everyday occurrence for P2P messaging (as most people's friends and family are serviced by different operators). Off-net messaging also occurs when a mobile phone is roaming.


Sending a message directly to the mobile operator associated with the mobile phone number. On-net delivery requires a direct connection.

one-way messaging

A messaging scenario where you send messages to your end users, but do not receive replies. For example, you can use one-way messaging for alerts and notifications. In the UK and much of the rest of the world, you can perform one-way messaging without needing a short code or text-enabled number, and can instead set the message sender as your brand name (or other alphanumeric string).

operator lookup

A synonym for mobile operator lookup.


The address from which a message originates. This can be a short code, VMN, toll-free number, landline number, or alphanumeric string.

over the air (OTA) updates via SMS

A type of binary SMS that enables mobile operators to send data to an end user's mobile phone as an SMS. It can be used for tasks like updating SIM cards or activating new services.


Over the top messaging. Internet-based messaging options on a mobile phone. Popular OTT services include WhatsApp, QQ Mobile, Facebook messenger, WeChat and Skype.

SMS was never considered a type of OTT messaging, as from early on it was an integral feature of a mobile phone. This is part of its advantage: unlike mobile apps or OTT messaging services, all mobile users — regardless of phone type, geographic location or data plan — can send and receive SMS messages. There is also no requirement to download an application and almost everyone is an experienced SMS user.


Overwriting refers to when a mobile operator (or supplier) changes the message originator field for a message to a different originator. The new originator may be a local number or an alphanumeric string. Overwriting may occur when your message originator is an alphanumeric string or internationally-formatted number.

This occurs in some, but not all, regions of the world. See our Global Coverage section if you want to find out whether overwriting occurs in a particular country or region you are messaging.



Person to Application. For information see A2P.


Person-to-Person or Peer-to-Peer. In SMS messaging, this is a message sent from one end user to another, such as when you message your friends or family.


Protocol Data Unit. A PDU contains message information, such as user data or address information.

prefix operator (or network)

In many countries, the mobile operators are assigned a number range from which they can provide mobile numbers to their customers. The number ranges are also normally reserved to just mobile phone numbers (rather than landlines). For example, in New Zealand, mobile numbers all begin with "02" followed by one or two digits that identify the specific operator; "01" for Orcon. Therefore, if a New Zealander provides a number starting "0201", you know immediately that it is a mobile number and the original provider of the number was Orcon.

In places where mobile number portability (MNP) is not supported, you can use the prefix operator rather than an operator lookup to determine the operator for a given number.

premium rate SMS

Premium rate SMS enables businesses to charge end users for an SMS-related use case. Normally a short code specifically for premium rate SMS is required. When the end user interacts via the short code, the mobile operator adds a charge to their account, and a portion of this is sent to the business. Enterprise use cases include: making charitable donations, charging for entry into a competition, and charging to vote in some form of popularity or talent event.

OpenMarket provides enterprise-level premium rate SMS in the UK, Ireland and Australia.


This is a term specific to US mobile messaging. It refers to a defined end user experience that meets the CTIA’s guidelines as well as operator-specific regulations and requirements. A program must include interactions that allow an end user to opt-in, opt-out, and access help. Additional details, such as how the program is promoted, are considered part of a program.

Before you can begin certain messaging programs in the US, such as short code messaging, you must provide a program brief to the relevant operators.

Program brief

A document required for US messaging use cases. It describes your mobile messaging program in detail, including the user experience and information about how the service will be promoted. Your program brief must meet CTIA guidelines as well as operator-specific regulations and requirements.

Your OpenMarket account manager will assist you in developing your brief to ensure that it your messaging program is not delayed due to mobile operator questions or requests for information.




Rich Communications Service is a communication protocol that enables multimedia content to be included in a mobile message, enabling companies to provide a richer and more interactive engagement between them and their customers. RCS messages have a mobile app look and feel but are sent and received like an SMS message.


The destinations to which an individual mobile operator can send messages. This includes off-net messages; e.g. their connections to other mobile operators both nationally and internationally. The reach of tier one operators, such as AT&T, is normally hundreds of other mobile operators globally.

read receipt

In RCS messaging, a read receipt is sent from the end user's phone to the message sender's system when the end user opens an RCS message.

retry schedule

If a message cannot be delivered to a mobile phone (for example, when the phone is turned off), then a retry schedule is used to attempt re-delivery. Both OpenMarket and the mobile operators have retry schedules. OpenMarket's retry schedule is used if there is an issue with reaching a mobile operator (such as during an unscheduled network outage). The mobile operators retry schedules are used when trying to reach the handset, or trying to deliver an MO message to an aggregator.

Retry schedules are not used for permanent issues where we have delivered an error message or failed delivery receipt to your system; such as if the mobile number is not valid or if the message is blocked by the operator.


A mobile phone outside of its coverage area "roams" to find another network to connect to. Roaming requires the mobile operator to have agreements in place with other operators internationally.

In Europe, roaming charges are regulated by the European Union roaming regulations, so that mobile operators cannot charge above a set rate.


sender ID

This term is synonymous with message originator.

shared short code

A short code used by multiple businesses. Traffic is routed to the individual businesses using keywords. In comparison, a dedicated short code is leased and used by only one business.

short code

A special telephone number that businesses can lease, which is significantly shorter than normal landline or mobile numbers. The benefit is that the shorter number is easily remembered by end users. Depending on the country, short codes are available for SMS messaging, MMS messaging, and mobile voice calls.

Short codes are provisioned within each mobile operator's system, rather than as part of a shared numbering plan reachable from anywhere. Therefore they cannot be reached internationally. To make it easier to provision a number across all operators in a country, often an administrative body will lease short codes on behalf of the operators, such as the CTIA in the US.


Subscriber Identify Module. A type of chip inserted in a mobile phone to identify and authenticate the phone with the mobile operator. The SIM stores a unique IMSI number and an authentication key. SIMs can also hold contacts.

SIMs are required in phones that use GSM or LTE, but not in CDMA phones. A SIM is intended to be transferable between phones. However, for end users subscribed to "phone plus SIM" contracts, some mobile operators will "lock" the phone to the SIM card, rendering the phone unusable with another SIM (normally until the contract ends).

Some phones come with two SIM slots, so that the end user can select between competing mobile operators; each SIM links to a separate mobile number.

smart message

This term is synonymous with binary SMS.


Short Message Entity. A device that can send or receive messages most often a smartphone. However, an ESME can also be considered a SME.


Short Message Peer-to-Peer protocol. An industry-standard protocol for exchanging SMS messages and data between systems.

OpenMarket offers an SMPP interface for SMS messaging, that supports version 3.4 of SMPP. However, if your business has not implemented this before, we instead recommend that you use our HTTP APIs, as these are easier to understand and implement.


Short Message Service Center. A core part of a mobile operator's infrastructure. SMS messages are first forwarded from an ESME to the SMSC. The SMSC then processes and forwards those SMS messages to the mobile operator’s network for delivery to an intended recipient. OpenMarket is an SMSC.

SMS fallback

In RCS messaging, if the OpenMarket system detects that a mobile phone is not capable of receiving an RCS message, it falls back to using SMS and sends a text message instead.

standard rate SMS

Standard rate SMS refers to the fee structure in the US and Canada for receiving an SMS message. Standard rate applies to messages received from other individuals (such as a friend) and from businesses that are not charging an additional fee (known as premium rate SMS) to receive the message.

Note that the vast majority of US and Canadian subscribers are on unlimited SMS messaging plans, and will not see a charge on their account. Standard rate SMS does not apply to most other regions and countries, as there has been no history of charging end users to receive SMS (aside from premium rate SMS).


A person who has a mobile phone account with a mobile operator. A related term is end user.


Ticket Id

The number returned in the body of the XML over HTTP response from the Enterprise SMS gateway upon a successful message submission

tier 1

Tier one refers to the infrastructure of a mobile operator. Tier one operators own their own physical wireless infrastructure and do not normally require a connection to another operator to interact with their subscriber base.

tier 2

Tier two refers to the infrastructure of a mobile operator. Tier two operators own their own physical wireless infrastructure; however, they purchase additional service coverage from other operators to reach their subscriber base.

tier 3

Tier three refers to the infrastructure of a mobile operator. Tier three operators are those that use the physical wireless infrastructure, such as cell towers, of other mobile operators. Without this access, they would have no means to interact with their subscribers.

A similar term is MVNO.


Time Division Multiple Access. A method for sending and receiving information wirelessly, such as over radio frequencies. TDMA takes advantage of digital encoding, which means that data (like audio) can be compressed during transmission. The cell tower tells the mobile phones when to transmit each segment of data and for how long, with the same frequency used by up to three mobile phones. The benefits of TDMA include allowing more mobile phones to connect to a cell tower, and improved transitioning between one cell tower to another tower (as a user geographically moves).

Related technologies are CDMA and FDMA.


Tag Length Value. Optional information that can be encoded within an SMPP operation. For OpenMarket, these include Mobile Operator ID, custom Note fields, and Status Codes. Different operations, such as MOs or MTs can use different TLVs.

toll-free numbers

Toll-free numbers are billed for all arriving calls. If an end user is using a landline, they are not charged to make a call to the number. However, depending on the region, mobile numbers may still be charged to make a call to a toll-free number.

You can SMS-enabled toll-free numbers in the US. However, messages sent to and from these types of numbers are charged as standard rate SMS to the end user. If you want FTEU messaging, you will need to use a short code.

A synonym is "freephone number".


Type of Number. This is an SMPP term for categorizing message originators, particularly in our APIs. It can help determine how an MT message is sent or routed. There are three TON categories:

  • Landline, toll-free, VMN, long code — any number that is provisioned nationally using the local country's numbering plans. These numbers could be reached internationally, and if you specify the number (in a request or MEP) we expect it to include the international calling code.
  • short code
  • Alphanumeric string — these are text strings, such as a brand name.


Transactions (or throughput) per second. A term used to describe how many messages can be sent per second. This is usually determined by the end operator's capabilities and number of binds that are being used for submission.

This is sometimes referred to as "messages per second" (MPS).

two-way messaging (2-way)

A messaging scenario where you send messages to your end users and expect to receive replies. For example, you can use two-way messaging to get feedback from your end users about a recent customer experience. You will need a short code or other text-enabled number provisioned in the region you are messaging.



This is a character encoding that can encode all of the possible characters specified in Unicode. It has generally been deprecated by UTF-16.


User Data Header. A user data header is an optional part of an SMS message that changes how the message is formatted or processed by a mobile phone. For example, a UDH is sent in an SMS if the SMS is one part of a multipart message. The limit on the size of an SMS includes any UDH.


User Interface. The part of a software application that you interact with. In our documentation, we use this term when talking about our web-based applications. For example, we use UI to differentiate between the MEP APIs and the MEP browser-based interface (UI).


Unicode is a computing standard created for handling the writing systems of almost all modern and historic languages. It ensures that, regardless of the character set used by a language, computers can encode, represent and transmit the data successfully.

Unicode was designed in conjunction with a Universal Coded Character Set (UCS), which assigns a "code point" for each character. Unicode character encodings, such as UTF-8 or UTF-16, then reference the UCS code point.


Coordinated Universal Time. The primary time standard commonly used world-wide, and is the basis for using the 24-hour time format. The UK and parts of western Europe are considered the starting point, or 0, of UTC. World-wide times are then specified as positive (+) or negative (-) from that UTC starting point. For example, New York City is UTC -5, while New Delhi would be UTC +5.3. This does not take into account any offset for Daylight Savings Time (DST).


A type of character encoding that can encode all of the possible characters specified in Unicode. It is a standard encoding for HTML documents, and is the dominant character encoding on the web. Benefits of using this encoding are that it is backwards compatible with ASCII and also takes less space than UTF-16 when encoding European languages.


This is a character encoding that can encode all of the possible characters specified in Unicode. It is a standard encoding for HTML documents.


validity period

The period during which OpenMarket and the mobile operator attempt to deliver an MT SMS to an end user. Validity periods are useful when you have time-sensitive messages, and do not wish end users to receive the message if it is delayed past a certain time. Common reasons why a message might be delayed (but still eventually delivered) include the phone being out of range or turned off.

A similar term is "expiry time".


A vCard is a binary SMS message that delivers the contact details for a person (or business). You can send vCards through any of the OpenMarket SMS or MMS messaging APIs.


Virtual Mobile Number. A VMN is a number provisioned for a business that looks like a standard mobile number to the end user. VMNs are normally provisioned for two-way messaging, and can receive messages globally.

For more information, including which originators are available in key regions, see Message originators.

Synonyms are "Long Code" and "Long Number".


WAP Push

 A type of binary message that uses SMS to deliver a hyperlink. The message body can also contain any text message you'd like to add. You can send WAP Push messages through any of the OpenMarket SMS APIs; however, we recommend using plain text messages instead, as some Smart Phones have been known to silently discard WAP Push messages. As well, most phones will now automatically turn URLs in plain text messages into hyperlinks.

wireless carrier

A North American term for a mobile operator.



eXtensible Markup Language. XML is a format used to send data between two systems. It was designed to be readable by developers as well as by machines, and is a popular format for sending data over the Internet. It is also "platform independent", which means that the systems exchanging data do not need to use the same platform or programming language (such as C++).

OpenMarket offers XML as a format option for our SMS API. We also offer JSON, which is a more lightweight format option and has become increasingly popular for use over the Internet.



Numbers & Symbols


Two-factor authentication. An authentication system that requires the end user to provide two forms of unique identification. Generally one identifier is a password or PIN and the other is a unique key. Examples of unique keys include a one-time password sent by SMS, a password provided in a mobile app, a code on an RSA key fob, or a fingerprint. SMS is a particularly well suited to 2FA as mobile phones are personal devices and SMS is ubiquitous, making it easy to deliver one-time passwords with confidence.