SMS: The Complete A-Z

From reducing no-shows to directing more traffic to your website, and boosting customer engagement – SMS really is the channel of choice. 

Whether you’re just starting out or looking to brush up on your SMS marketing knowledge, our complete A-Z glossary has got you covered.




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 all you have to do is plug into an SMS API and you gain message sending/receiving capabilities almost instantly!

Auto response

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


Bulk SMS

Or mass/bulk texting allows businesses to send text messages to large groups of mobile numbers at once. It’s a great way to quickly and effectively reach a big audience with offers, updates, reminders and more.


Call to action

Usually shortened to CTA, a call-to-action is your prompt to persuade/encourage your message recipient to do something. It could be following a link to your web page or socials.  The clearer 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 whilst saving human resources. There’s always the option to escalate chats to a live agent, but having a chatbot as the first step can filter out the more repetitive cases so customer service representatives can work on more complex cases that require human attention.

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 and multiplying by 100 to get the percentage. 

So, if you sent a text to 200 people and 20 of them clicked on your CTA, your CTR would be 10%.


Digital letter

Known as a mobile letter too, digital letters are documents that are sent to a mobile device via an automated, and 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 and ask them to verify their ID.

After doing so, the recipient can securely view/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 offer value.

Email to SMS

An email to SMS service enables you to send an SMS through your email provider. Via a gateway, you can immediately start sending text messages with the familiarity of doing so from your existing email provider.



A gateway – or SMS gateway, in this context – 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.

Question: 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 rich features like images, audio, video and other media with your text.

Mobile journey

A mobile journey is a path that you direct users along and towards a goal – usually 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 that provides its subscribers with internet and telecommunications services. Popular network operators include Vodafone, EE, and O2.


One-time password

An OTP is a password/code that is valid for a single 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 consent for you to text them (opt in) or revoked consent (opt out). It’s important that your opt-in process is clear and simple to attract as many sign ups as possible, and it should also be easy to opt out.



A personalised SMS message is one that singles your customer out in some way by using information unique to them. This could be as simple as addressing your recipient by their first name or sending them offers and promotions tailored to their purchase history.

An SMS messaging platform will have the functionality to insert personalisation tokens or dynamic fields that will pull data from your integrated CRM system – so that the personalisation process can be automated.



A reseller is a business that partners with an SMS provider to enable message sending capabilities for their customers -and then resells this ability to earn commission.


Sender ID

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

Short code

This is a five or six-digit number that is used to send or receive text messages. Short codes are most commonly 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 SMS messages.


Text credits

This is the ‘currency’ that is used 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 sent to users/customers with essential information that follows up on transactions/interactions they’ve had with a business. For example, if a customer places an order, an order confirmation or order dispatch text both would be classed as transactional SMS messages.

OTP SMS messages are also classed as transactional.

Two-factor authentication

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

You’ve probably come across this a lot before in the form of an OTP, or biometrics (e.g. fingerprint access).


Virtual mobile number

Also known as a VMN, a virtual mobile number is what you’ll need if you want to start a two-way conversation over SMS. When you use a VMN, your messages won’t have a Sender Name – they’ll come from a number. 



An automation that allows you to set up a process for what happens at various points of a customer’s journey. For example, if a customer makes a purchase, a workflow can automatically send SMS messages or other communications to follow-up with their order.

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