SMS marketing rules in Australia: consent, sender details and unsubscribe for follow-up texts

If your business texts leads and customers, the SMS marketing rules in Australia come down to a few questions. Is the message commercial? If it is, do you have consent you can prove? Does the text say who you are and how to reach you? Can the recipient unsubscribe easily? The Spam Act covers all of these, and the ACMA enforces it. It has also become stricter about branded Sender IDs.

This guide goes through each question from the angle of a business sending follow-up texts: after an enquiry, after a quote, or to old leads you'd like to bring back.

When is a follow-up text "commercial"?

Most problems start here. Plenty of businesses assume a friendly "just checking in" text is fine because it isn't a promotion. But if the text is selling, or nudging someone towards buying, it is probably a commercial message.

The ACMA says messages are generally not spam if they have no advertisements, are appointment or payment reminders, notify a service or product fault, or are about a service the person uses. So a reminder of tomorrow's booked appointment usually sits outside the spam rules. A text that says "Still thinking about that quote? We've got a special this week" does not.

Automated sequences need particular care. The ACMA says automated SMS and email "welcome journeys" sent to new and prospective customers often contain commercial content and must comply with the spam rules. If your CRM sends a series of texts after someone fills in a form, read each message as the recipient would. If any of them promotes, offers or upsells, treat the whole sequence as commercial.

A useful test for your team: if you took out the selling, would the message still be worth sending? If it wouldn't, it's commercial.

When you need consent, and what counts

The basic rule

Under the ACMA's guidance, a business must have consent from each recipient before sending marketing emails or messages, even if someone else sends them on its behalf, and it is up to the business to prove it has a person's consent. Using an agency, an SMS platform or a contractor doesn't move that responsibility off you.

Express consent is the safer path

The ACMA recommends express consent based on clear terms and conditions, readily accessible where consent is given, that explain what the marketing is for, who will use it, how long it will be used and how consent can be withdrawn.

It also says businesses should not use pre-checked tick boxes, bundled consent or refer-a-friend arrangements to obtain marketing consent. That means a marketing opt-in tucked inside your general terms, or a box already ticked on your enquiry form, is weak ground.

Inferred consent is narrower than most people think

Inferred consent is where many follow-up programs go wrong. The ACMA says inferred consent usually needs a provable, ongoing relationship that the marketing directly relates to, and it does not cover sending messages after someone has just bought something.

It also warns that automatically adding someone to a marketing list after a one-off purchase, or because they simply submitted an enquiry, may breach the consent requirements. For lead follow-up this matters a lot. An enquiry on its own doesn't give you permission to put someone into a promotional text sequence.

Published contact details don't help either. Under the Spam Act 2003, consent can't be inferred merely because an electronic address was published. The exception is a conspicuously published work address with no statement refusing marketing, where the message is relevant to the person's work role. A mobile number scraped from a directory isn't permission to text it.

You can't text to ask for consent

A tempting shortcut is to text old leads and ask "Can we keep in touch?" The ACMA is clear that a business cannot send an electronic message asking for consent to marketing, because that message is itself a marketing message. Collect consent at the point of enquiry, on the form, on a call or in person.

Keep records you can produce

The ACMA expects consent records to show how consent was obtained, the terms that applied, and the date and time it was obtained, and such records must be produced if the ACMA requires them. In practice, for every contact you text, you should be able to pull up:

• The form, call or channel where consent was given
• The wording or terms shown at that moment
• The date and time stamp
• Whether consent has since been withdrawn

If your CRM can't show this for a contact, leave that contact out of commercial sends until you've sorted it.

Identifying the sender

Every commercial text has to say who sent it. A commercial email or SMS must accurately identify the business that authorised it and include its contact details, and that information must remain correct for at least 30 days after the message is sent.

For SMS, where space is tight, that usually means:

• The business name the recipient will recognise, not just a brand nickname or a staff member's first name
• A contact method that works, such as a phone number, website or email
• Details that stay valid, so don't use a temporary campaign number you'll switch off next week

Texts that sound personal ("Hi, it's Sam!") are common in sales follow-up. They're fine as a tone, but the message still needs to identify the business clearly.

A working unsubscribe

Under the Spam Act, every commercial message needs an unsubscribe option that is clearly presented, honoured within 5 working days, free apart from the usual cost of sending, functional for at least 30 days, and does not require logging in or giving extra personal information.

Questions to check with your SMS provider or internal team:

• Does a STOP reply actually remove the number from every list and every automated sequence, not only the current campaign?
• How long does the opt-out take to sync across systems, and is it inside 5 working days?
• If you send from more than one platform, do the platforms share opt-outs?
• Will an unsubscribe link keep working after the campaign ends?
• Does your opt-out page ask people to sign in or fill in a form? If so, simplify it.

Why replies to a Sender ID don't work

A Sender ID is the alphanumeric name, such as your business name, that shows in place of a phone number. It looks professional, but it carries a catch. The ACMA warns that people generally cannot reply to an SMS sent with a Sender ID, so an unsubscribe process that relies on replying to a Sender ID does not work and will break the law.

If you use a Sender ID, "Reply STOP to opt out" is not a valid unsubscribe. Your choices are:

• Send from a phone number that can receive replies, and process STOP replies properly
• Keep the Sender ID and include an unsubscribe link or another opt-out method that works without replying

The cost of getting this wrong is real. The ACMA's 2026 investigation outcomes list a $3,960,000 infringement notice and enforceable undertaking for Latitude Finance Australia over marketing SMS sent without adequate sender contact information and without a functional unsubscribe facility.

The Sender ID Register

Branded texts now come with a registration requirement. Businesses that send texts with a Sender ID must register it through their telco or message provider, and from 1 July 2026 an unregistered sender ID is replaced with the word "Unverified". Businesses sending from a phone number don't need to do anything.

If your follow-up texts arrive labelled "Unverified", expect fewer replies and more people treating them as scams. Ask your provider to confirm that every Sender ID you use is registered, including any old campaign names still sitting in your automations.

What happens if you get it wrong

Where the ACMA finds breaches, it can take the matter to the Federal Court, give an infringement notice, issue a formal warning or accept a court-enforceable undertaking. In July 2026 it said businesses had paid more than $12 million in penalties for spam and telemarketing breaches over the past 18 months. It also reported that TAB paid more than $2.7 million for breaches that included 351 calls to numbers on the Do Not Call Register without consent, 82 calls outside permitted hours and nearly 4,000 calls without properly identifying the caller or purpose.

A practical checklist for follow-up texts

• Sort every automated text into commercial or non-commercial, and treat mixed sequences as commercial
• Get express, unbundled consent at the point of enquiry, with clear terms
• Store how, when and on what terms consent was given
• Never text to ask for consent
• Name your business and give working contact details in every commercial text
• Make sure the unsubscribe works, especially if you use a Sender ID
• Register every Sender ID with your provider
• Check the rules for your situation with the ACMA or a lawyer

Where voice fits

Texting isn't the only way to follow up. Under the Spam Act 2003, a message sent by voice call over a standard telephone service is not an electronic message for the purposes of the Act. Calls still have their own rules, as the TAB matter shows, so check what applies to you with the ACMA or a lawyer.

This is why we built Dialessa around calls. It's an AI voice agent that calls new enquiries within a minute, inside your calling hours, asks your qualifying questions and books the appointment into your calendar. Your texts can then be used for what they handle best: confirmations and reminders, with the sender clearly identified and an opt-out that works.