How SMS opt-outs (STOP) work

What happens when someone replies STOP?

When a reply to one of your numbers is the word STOP on its own, in any capitals, Enfonica immediately adds the sender's number to your project's unsubscribers. This is on by default for every project. It works whatever sent the original message: the API, SMS Marketing, email-to-SMS, or an app such as 3CX.

The reply still arrives like any other incoming message, so your system or your team sees it too. A reply with other words around it, such as "Stop please", isn't treated as an opt-out. For more information, see Do other replies opt people out?

Which messages does an opt-out stop?

It depends on how each message is classified. Messages you send with the API are unclassified unless you say otherwise.

When a message is blocked, the API refuses it with the error Recipient is unsubscribed, and nothing is sent or charged. In SMS Marketing, a campaign of the marketing type leaves out people who have opted out. A transactional campaign doesn't.

Is an opt-out for one number, or the whole project?

The whole project. An opt-out applies to every message sent from that project to that person, from any of your numbers or sender IDs. A STOP reply to one campaign also stops the next one.

Your other Enfonica projects aren't affected. If you send for several brands or clients, send for each one from its own project to keep their opt-outs separate.

Do other replies opt people out?

By default, only STOP on its own opts people out. Two other options are available:

• An extra word list. We can turn on a list of abusive and profane replies that also opt the sender out. This suits survey and research messages. To turn it on for your numbers, contact us.
• Your own rules. If your system handles incoming messages with a webhook, it can opt someone out for any reply you choose. To do this, it answers with the MessageML <Unsubscribe/> action. For more information, see MessageML.

What about messages from a sender ID?

Nobody can reply to an alphanumeric sender ID, so a STOP reply can't reach you that way. Give people another way to opt out:

• SMS Marketing. A marketing campaign from a sender ID must have an Unsubscribe phone number, which is one of your SMS-enabled numbers. The opt-out line tells people to reply STOP to that number.
• The API. Set unsubscribeContentBehavior to APPEND_URL. Enfonica adds a short unsubscribe link to the end of the message, which the person can use to opt out.
• One-off messages. Send from one of your numbers instead, and end the message with "Reply STOP to unsubscribe."

What does SMS Marketing add to my campaign?

A campaign of the marketing type ends with Opt-out reply STOP. When you send from a sender ID, it ends with Opt-out reply STOP to, followed by your unsubscribe number.

If your message already contains the word STOP in capitals, nothing is added, so you can word the opt-out yourself. Transactional campaigns don't add a line.

How do I see or remove unsubscribers?

In the Enfonica Console, go to Cloud SMS > Unsubscribers. The page lists every number that has opted out of the project, with how it opted out and the date. To download the list, select Export.

To remove a number:

1. Select Remove next to the number.
2. To confirm, select Remove again.

Messages to that number are sent again from then on. Remove a number only when that person has asked to hear from you again, such as when someone opts out their own phone while testing.

Developers can manage the same list with the Unsubscribers API.

Can opt-outs be turned off?

Not by default, because they're a safeguard for you and the people you message. Another platform you use, such as a survey platform, might keep its own opt-out list. If you'd rather rely on that list, contact us to talk through the options for your project.

Does this make my messages compliant?

It helps, but it isn't the whole picture. You're responsible for the compliance of the SMS you send.

In Australia, commercial electronic messages, including SMS, are covered by the Spam Act 2003. The Australian Communications and Media Authority (ACMA) enforces it. Enfonica's opt-out handling helps you honor unsubscribe requests. To check what applies to the messages you send, see ACMA's guidance for businesses.