SMS glossary: the meanings of the tricky words and acronyms

There are many words that we have thrown around over the years that have created confusion among our customers and users. API? GSM? Gateway? What do the words actually mean? You will find the answer to these and many more terms below in our SMS glossary.


Application-To-Person. SMS sent from an application to a mobile phone (person). For example, one-time passwords, bank notifications or booking confirmations via API or Web application.

AI Chatbot

A chatbot is an artificial intelligence (AI) program that can send automated voice and text messages in text chats. Chatbots can be used for mobile messaging, web pages or other digital applications to answer simple and complex customer inquiries without the need for human agents, providing affordable and accessible customer service. With the correct background data, the bot can be very personal and adapt responses based on customer, context and intent.

Alphanumeric sender-ID

Sender ID refers to where messages are sent from. This can be alpha (contains characters and numbers), numeric (numbers only) or a numeric shortcode.

Apple Messages for Business

Standard mobile application for IOS (Iphone) that has features for businesses to send rich messages to customers.

Binary SMS

Binary messages are messages that require specific encoding to overcome the character limitation in an SMS message. Binary messages are used for specific characters in languages such as Arabic, Chinese, Korean, Japanese, or Slavic languages (eg Russian).


A list of recipients who have opted out of SMS. SMS are therefore not sent to these recipients.


SMS sent in large volume.


Contact Center as a Service. CCaaS solutions include a variety of communication features (Mobile Channels, Web Apps, Workflows, Chatbot, Voicebot, APIs) that make it easier for businesses to communicate with customers.


Customer-Data-Platform is software that collects customer touch points and interactions with your product or service from various channels and sources.


IT services provided digitally over the internet.


Computer Interface to Message Distribution is a proprietary short message service center protocol developed by Nokia for their SMSC (now Nokia Networks).


Composition of strings (in computer programming). SMS Gateway splits and assembles long SMS messages (more than 160 characters) automatically, both incoming and outgoing.

Conversational AI

Conversational AI (artificial intelligence) technology enables bots to engage in natural-sounding text conversations with customers.

Cookie-free data collection

Cookie-free data collection collects user data and insights without using website cookies (data trackers that contain personal identifiers). This type of data collection is becoming more common with new tracking restrictions and privacy regulations.


Communication-Platform-as-a-Service. For example, our platform.


Call-To-Action. Interactive buttons in a message that can, for example, lead to a landing page. For example "contact us".


Click through rate.


Conversion rate.


Customer experience.


Data-Coding-Scheme. DCS is a field in Short Messages (SM) and Cell Broadcast Messages (CB) that contains basic information about how the receiving handset should process received messages.

Direct dialing (DDI – Direct Dial In)

Direct Inward Dialing (DID) or Direct Dial In (DDI) is a service provided by a local telephone company or local exchange operator that provides a block of telephone numbers for calling a company's private branch office (PBX) or IP telephony system. With the help of DDI, companies can offer their customers individual phone numbers for each individual or workstation within the company. This without requiring a physical line to the exchange for every possible connection.


Delivery reporting. A DLR shows the status of a sent message. Once the message has been received (or not) within the 48-hour interval, the sender (company) or aggregator (aggregator) receives a delivery status report detailing the processed message.


Dual-Tone-Multi-Frequency is a method used in IVR systems to select menu items or enter codes. DTMF is often used for telecommunications signaling over analog telephone lines in the voice frequency band and in touch-tone telephones.


End-To-End-Encryption. Communication systems where only the communicating users can read messages.


Emails that are converted to SMS after sending. You can use any email program to send SMS through a Gateway.


A kind of pictogram that can be used in text messages to express emotions in different genres, for example, 😃👍📱.


External-Short-Messaging-Entities are external applications that connect to an SMS service to send and receive SMS. Examples of ESME are voting systems or automated marketing messages.

Facebook Messenger

Facebook Messenger is a mobile application for smart mobile phones that has features for sending instant messages, sharing photos, videos, audio recordings and creating group chats between Facebook Messenger users.


Messages that appear to be from a sender they are not.

False DLR

False DLRs are a known problem among aggregators. In a false DLR, the provider of a connection falsely reports a successful delivery to an end-user device. This results in companies paying for messages that are never delivered to a device.


An FAQ chatbot can be used to automate answers to some of the most common questions your organisation may receive. These types of questions can be a huge burden on your customer service team and often involve repetitive, copy & paste responses that are handled more easily and efficiently by a machine.

Fixed Sender ID

Fixed Sender ID is a predetermined numeric Sender ID that cannot be changed according to the user's needs. This is a mobile number that appears on the recipient's mobile phone.

Flash SMS

Flash SMS is displayed directly on the mobile screen and the user therefore does not need to go to the mobile phone's inbox to read messages.

First Party Data Collection

First-party data is customer data collected with consent and owned directly by your company (the data controller). The data is a valuable source of customer insights.


The General Data Protection Regulation is an EU regulation that prescribes the precautions companies must take to protect citizens from privacy and data breaches, including how to handle breach notifications. Companies should be aware of which GDPR rules apply to opt-in and opt-out in customer communications.


Graphics Interchange Format. Standard for non-destructive compression of images. GIFs can be sent via most messaging channels.

Gray routes

Less calculated providers use back roads in the mobile operators' networks, so-called gray routes, to avoid paying for their traffic.


Global System for Mobile Communications or GSMA = GSM Association. A trade association that represents the interests of mobile network operators worldwide.


160 characters is the limit for messages encoded using the GSM-7 character set. If the message is not encoded with GSM-7, the limit is 70 characters.


The Home-Location-Register is an MNO database that contains all information related to a mobile subscriber's device. For example, HLR data can be used to verify number information and prevent fraud.

Hybrid messaging

Hybrid messages allow you to send push messages as an SMS, e.g. if the recipient does not have your app installed or is offline, the message is sent via SMS. This way you will achieve the highest reach at the lowest cost. If you don't have your own app, you can use a push notification application that supports SMS fallback.


International Mobile Subscriber Identity unique for each SIM card. The IMSI code is related to a SIM card and even if the phone number is used again by another user, the SIM card will be printed and given a new IMSI code.


Instagram is a mobile application for smart mobile phones that has features for sending text messages, pictures and videos.


Interactive-Voice-Response is an automated telephone system with call routing. The system answers incoming calls and prompts customers to interact with a pre-recorded message or series of messages.


KakaoTalk is a mobile application for smart phones that has features for voice and video calls, instant messaging, and other features such as location sharing, games, and scheduling. The app has approx. 50 million users and is common in South Korea.


Keyword is a short word consisting of letters and/or numbers. The keyword is the first of two fundamental components of any successful SMS marketing campaign. The customer must send specific keywords to the shortcode to trigger a response.


A metric to measure the quality of customer interactions (clicks, opens, conversions, churn, quality of service, NPS and more).


Line is a mobile application for smart phones that has features for voice and video calling, instant messaging and language translation. LINE has approximately 165 million users and is common in Japan, Taiwan, Thailand and Indonesia.

Long SMS

Messages of up to 804 characters. Most mobile networks can segment SMS messages up to 1600 characters and concatenate them into an SMS message to the recipient.

Long code

A long code or long number is a virtual phone number of standard length (10 digits) that can be used by businesses to send and receive text messages, or to make and receive voice calls. They are cheaper to use than short codes.

Marketing Automation

Marketing automation refers to the use of software and technology to automate and improve marketing activities, such as email campaigns, SMS campaigns, social media ad campaigns, chatbot conversations, tracking, A/B testing and more.

Message Log

The SMS platform's message log records information about each message in real time and enables a variety of filters in the platform. For example, period filters (month, year, day), routing filters (gate, carrier, country, etc.), content filters (message ID, sender, text), and option filters. This is the first thing you should look at if there are problems with your SMS traffic.


Mobile-Country-Code. Used in wireless telephone networks (GSM, CDMA, UMTS, etc.) to identify the country to which a mobile subscriber belongs.


Mobile-Network-Code. The code is either a two- or three-digit number used to identify a mobile network in a specified country. MNC is used as part of IMSI (International Mobile Subscriber Identity) and LAI (Location Area Identity).


Mobile-Network-Operators. Mobile network operators such as Telia, China Mobile or AT&T.


Mobile-Number-Portability. A telephone number registered with one MNO can be transferred to another MNO. For example from Telia to Tele2. During the transfer process, the end user receives a new SIM card printed containing an IMSI code from the new MNO, which is necessary for the new Mobile Operator to be able to route data, voice, SMS, etc.


Mobile-Originated-SMS. A message sent from a mobile phone to another mobile phone (M2M) or to an application (M2A).


An MSISDN is the phone number associated with an individual SIM card and is the number to which you call or send an SMS message. The MSISDN is used to identify a mobile user when they call or send an SMS.


Mobile-Terminated-SMS. The message is terminated (delivered) on a mobile device (also known as an outgoing SMS).


Net Promoter Score. A market research metric used in customer surveys.

Numeric Sender ID

These sender IDs consist of numeric characters only.


A marketing strategy that uses several different contact surfaces to connect with customers in order to create a seamless customer experience.

Operator billing

Carrier Direct Debit is an online payment method that allows users to make a purchase by charging payments to their mobile phone bill. Carrier billing is available to all consumers with a mobile device containing a SIM card.


When a customer approves communications from companies.


When a customer declines communications from companies.


Over-The-Air. An MT SMS feature that sends wireless configuration messages, such as software updates, configuration settings, and security locks.


One-time password. Maintains high security and reduces the risk of fraudulent login attempts.


Over-The-Top. Messaging apps such as WhatsApp and Facebook Messenger


Person-to-Application. SMS sent from a mobile phone (person) to an application.


Person-to-Person. Text messages sent from person to person.


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We use our proprietary platform, which enables our customers to reach out with internal and external communication, both through targeted sendings and mass sendings.

Push notifications

A push notification is a message that appears on a mobile device, such as an acknowledgment, a reminder, or an alert. App publishers can send them at any time, as users don't need to be in the app or use their devices to receive them.


Qwerty is the most common keyboard layout.


Rich Communication Service. Send branded messages with rich content. Future replacement for SMS as the default messaging app in Android.

Rich SMS

A rich SMS experience with landing page.


Return-Of-Investment. A performance measure used to evaluate the effectiveness or profitability of an investment.


The path that an SMS takes between sender and recipient. The ability of SMS providers to choose between different routes can help improve the quality of SMS delivery.


Software Development Kit. SDK stands for software development kit, also known as devkit. An SDK is a set of tools for a specific platform, containing debuggers and a framework/group of code libraries (a set of routines specific to, for example, an API and operating system).

SIM farms

SIM farms illegally take advantage of the favorable fixed price offers for SMS that operators offer to ordinary consumers.

SIP trunk

Session Initiation Protocol. SIP trunking is a service offered by communication service providers. The protocol is used to provide voice over IP (VoIP) connectivity between a local telephone system and the public switched telephone network (PSTN).


Service Level Agreement Defines the level of service expected by a customer from a delivery.


Subscriber Identity Module. The SIM card is used to enable communication between different mobile devices over a 2G/3G/4G telecommunications network.


Like Faking, smishing is messages that appear to come from a sender it's not really from.


Short Message Service. Standard feature in mobile phones that allows users to send and receive messages.

SMS aggregator

Intermediary between companies that want to interact with end users and mobile network operators.


Application Programming Interface. Predefined instructions (a kind of software service) that enable your systems and applications to send SMS globally via an SMS Gateway.


Short-Message-Service-Center. SMSC is the part of a mobile phone network that handles text messaging operations. It is responsible for receiving, storing, routing and forwarding SMS messages from mobile phones.

SMS firewall

An SMS firewall is a security system that measures incoming and outgoing traffic to find things that go wrong or that shouldn't be there.

SMS fallback

SMS fallback extends the functionality of a push notification by delivering your push messages as SMS messages instead. For example, companies can set up SMS backup when data traffic is not available.

SMS Gateway

Conversion between SMS and other media. For example, e-mail can be converted to SMS or vice versa.

SMS short code

Bulk SMS with five or six digit numbers.


An open industry standard protocol for SMS. Allows applications to send and receive SMS messages to and from mobile devices.


Unsolicited or illegal text messages.


In the case of spoofing, SMS distributors use the opportunity to define the sender of the message themselves in order to intentionally mislead the recipient or other actors in the supply chain.


Signaling System #7 (SS7) is a set of telephony signaling protocols used to connect most of the world's public telephone calls. This system is also used in mobile messaging, prepaid billing and other applications.

TON/NPI Settings

This MT SMS feature allows senders to manage sender and destination settings.

Transactional SMS

Transactional SMS is used to notify about account updates, transaction updates, delivery updates, order updates.

Two-factor authentication (2FA)

An extra layer of security at login to ensure that only you can access your account.

Two-way SMS

Messages that are both sent and received. A combination of outgoing (Mobile Terminated or MT) and incoming (Mobile Originated or MO) SMS into a complete service. This means that the end user can reply to an SMS sent from a company or an app. 2-way SMS messages are made using short codes or long codes (numbers).


An industry standard that allows computers to handle text in different writing systems.

Verified SMS

Verified SMS adds a layer of authentication to standard SMS messages by displaying your business name, logo and verification mark in your business messages.


Viber is a mobile application for smart phones that features end-to-end encryption, text and video messaging, and voice calling. The app has been downloaded by approximately 1 billion users primarily in Greece, Eastern Europe, Asia and the Middle East.


Converts text to speech and is used e.g. for notifications and two-factor authentication. The service calls and reads the message, and can offer different response options via DTMF.

WAP Push

Wireless Application Protocol. A WAP Push is a specially coded message with a link to a WAP address. The recipient can then connect directly to a specific URL via the mobile phone's WAP browser, instead of having to copy and paste the link into the mobile phone's browser.

Web app

In addition to API and SDK integration, we offer most products as web apps. By creating customized web apps in our platform, you can easily distribute access to these depending on the area of use and business.


Mobile application for smart mobile phones that has features for voice and video calls, conference calls, video games, photo and video sharing and location sharing. The app is mainly used in China.


WhatsApp is a mobile application for smart phones that features end-to-end encryption, interactive text and video messaging, templates, and voice calls.


A set of rules that perform a series of automated steps or operations. For example, an automatic marketing SMS can be sent out when a new lead opts in.