SMS messaging: The A-Z glossary

From boosting marketing campaigns and increasing sales to reducing missed appointments and enabling customers to reach out via their preferred channels, SMS is an essential component of your business communication strategy. Just starting with SMS? Or maybe you’re looking to deepen your understanding of SMS.

No matter your experience with this medium, here’s our comprehensive A-Z glossary of SMS messaging.




Short for Application Programming Interface, an API allows you to access the features and functionalities of another software without needing to deploy it. Let’s say that you wanted to start sending and receiving SMS messages. Simply plug into an SMS API and you gain message sending/receiving capabilities within minutes! 

Auto response

This is a type of SMS message that’s automatically generated in response to an inbound message. A good example is an out-of-hours text message that would be sent if a customer reaches out to you outside of business hours.


Bulk SMS

Also known as mass texting, a bulk SMS service allows you to send text messages to a large group of mobile numbers. It’s a great way to quickly and effectively reach a large audience with offers, updates, reminders and more.


Call to action

Often shortened to CTA, a call-to-action is your prompt to persuade/encourage your message recipient to do something. It could be a URL that you want them to click on or an eBook to download. The clearer and more valuable your CTA is, the more likely people are to interact with it.


This automated messaging agent will allow you to have conversations with customers and prospects without needing to assign human resources. There’s always the option to escalate chats to a live agent if the bot can’t resolve it, but a chatbot can handle the more repetitive cases so customer service representatives can work on the issues that truly require human intervention. 

Tip: Have a look at your historic customer cases and customer care scripts. Are there any frequently asked questions that could be automated via a chatbot?

Click through rate

Click-through rate (CTR) is a metric that measures the ratio of clicks you receive on a specific link to the number of times your page, ad, email or SMS message is shown. It’s calculated by clicks ÷ impressions. 

So, if you sent a text to 100 people and 20 of them clicked on your CTA, your CTR would be 20%.


Digital letter

Also known as a mobile letter, digital letters are documents that are sent to mobile devices via an automated, secure process. Instead of a PDF attachment, the recipient is sent an SMS with an embedded URL which informs them that they have a document waiting to be viewed. The link will take the recipient to a web page which asks them to verify their ID.

After doing so, the recipient can securely download the letter/document straight to their device. 



This is a metric used to assess the number of interactions your message receives based on the total number of recipients. Want to improve your SMS engagement rate? Ensure that your texts are always clear, concise and get straight to the point, and that you’re offering value with every message.

Email to SMS

An email to SMS service allows you to send SMS messages via your email provider. Via a gateway, you can immediately start sending text messages from the comfort of your existing email provider. 



A gateway – or SMS gateway, in this case – is a piece of networking hardware or software that allows a computer to send and receive SMS messages to and from an SMS-enabled device over the global telecomms network. It converts the information/data it receives into the appropriate format (protocol) before sending it to the destination network and ultimately, the recipient.

What’s the relationship between an SMS gateway and an SMS API? An API allows you to connect to a gateway, which then unlocks the SMS message sending capabilities in your existing solutions.



Short for multimedia messaging service, an MMS message allows you to include images, audio, video and other media as well as text.

Mobile journey

A mobile journey is a path that you direct users along and towards completing a specific task or set of tasks. For example, you may want to collect payments. It will start with an SMS or email that includes a URL. Upon clicking on the link, the recipient will be taken to a secure, branded web experience (a series of web pages, for instance) where they can make a payment, change their payment plan or details, speak to a live agent and more.


Network operator

This is the company via which your mobile messaging service is provided by. Examples of well-known network operators include O2, EE and Orange.


One-time password

An OTP is a password/code that is valid for just one login session. It is a form of two-factor authentication. This password is typically sent to your smartphone and you must enter it to authenticate yourself.

Opt in/opt out

This refers to whether a person has given permission for you to text them (opt in) or revoked that permission (opt out). It’s important that your opt-in process is clear and simple. It should also be easy to opt out.



A personalised SMS message could be as simple as addressing your recipient by their first name or sending them offers and promotions tailored to their specific needs. For example, product recommendations based on their purchase history or offers based on their location.

An SMS messaging platform will allow you to insert personalisation tokens or dynamic fields that will pull data from your integrated CRM system. So, the personalisation process can be automated.



A reseller is a business that partners with an SMS provider to provide message sending capabilities to their customers and effectively, resells this ability to earn commission.


Sender ID

This is the name that appears as the ‘From’ name on the recipient’s handset.

Short code

This is a five or six-digit numbers that can be used to send or receive text messages. They’re usually used to send marketing messages, mass notifications, alerts or verification codes. 

SMS marketing

This is a type of marketing that businesses use to send promotions, offers and educational resources to customers via text messages.


Text credits

This is the ‘currency’ you use to send each text message. One credit will allow you to send one 160-character message. These are typically bought in bulk from your SMS provider.

Text to win

This is the process by which people can text their answer to enter a competition. Entrants will be sending their answer to an SMS short code. 

Transactional SMS

Transactional SMS is a type of message that you send to users/customers with essential information that follows up on transactions/interactions they’ve had with your business. For example, if a customer places an order, an order confirmation or order dispatch text would both be classed as transactional SMS messages.

Another example is if a user is trying to log into their account and they receive a one-time password. The text that contains the OTP is a transactional SMS.

Two-factor authentication

Also known as multi-factor authentication (MFA), 2FA is an electronic authentication process that requires users to successfully present two or more forms of identification before they can access a website, app or set of data.

Some examples of identification include a password, a passcode (OTP) sent to your smartphone or biometrics (e.g. fingerprint access).


Virtual mobile number

Sometimes abbreviated as VMN, a virtual mobile number is what you’ll need if you want to have two-way conversations over SMS. When you use a VMN, your texts won’t have a Sender Name – they will come from a number. 



An automation that allows you to set up and deploy a process for various points of the customer journey. For example, if a customer purchases a product, a workflow can automatically send SMS messages or other communications to follow-up with the customer.

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