SMS follow-up after a call: cadences, templates and the Spam Act rules

Every AI call should end in a text. If the call connected, the SMS confirms what was agreed. If it didn't, the SMS replaces the second and third unanswered ring. Done well, these texts reduce no-shows, catch misunderstandings and give people a way to respond on their own time.

This article covers the cadences we recommend, sample wording, and the Australian rules for business texts. It's part of our guide to AI voice agents in Australia.

Transactional or marketing: decide before you write

The Spam Act regulates commercial electronic messages, which includes SMS. Its Schedule 1 carves out "designated" messages that consist of factual information plus limited extras such as your name, logo and contact details. Those don't need consent or an unsubscribe facility, but must still identify the sender accurately. Most post-call texts can and should be in that factual category.

ACMA has repeatedly flagged businesses that dress marketing up as service messages. Its list of common issues and mistakes includes shipping emails with ads, "welcome journeys" and retention messages, and it notes that breaches can occur even when a message is mostly factual. Our rule: if any line of the text is trying to sell, treat the whole text as marketing.

Consent, identification and unsubscribe for marketing texts

If a text is commercial, ACMA's guidance summarises the three obligations:

• Consent. Express (a ticked box, a recorded verbal yes on a call) or, in narrower cases, inferred from an existing relationship where the marketing relates directly to it. A one-off purchase alone doesn't support inferred consent. Keep a record of who consented, when and how; the onus is on you to prove it. And you can't send a text asking for consent, because that text is itself marketing.
• Identification. Name the business that authorised the message (legal name, or name plus ABN) and include contact details that stay accurate for at least 30 days.
• Unsubscribe. Clear instructions, no fee beyond a standard text, working for at least 30 days, no log-in or extra personal details required, and honoured within five business days.

One practical trap: "Reply STOP" only works if people can reply. ACMA points out that alphanumeric sender IDs generally can't receive replies, so an unsubscribe that relies on replying to one doesn't work. Use a reply-capable number or include a free-call number or link for opting out.

Voice consent captured by an AI is still consent, if it's clear. If an agent asks "Would you like us to text you occasional offers?" and the customer says yes, log the question, the answer and the timestamp against the contact. Our view: don't ask for marketing consent on a service call at all unless it's genuinely relevant; it erodes trust in the confirmation that matters.

Sender IDs: the 1 July 2026 change

Branded texts that show your business name instead of a number now depend on ACMA's SMS Sender ID Register. Since 1 July 2026, sender IDs must be registered through your telco or message provider; unregistered ones display as "Unverified" and are grouped with other unverified messages, including scams. A sender ID must be 2 to 11 characters, can't be only numbers and must link clearly to your organisation; if you have an ABN, it must match your registered business name, company name, trademark or domain name. If you text from an ordinary phone number, the register doesn't apply.

Which to choose? A registered sender ID builds recognition and helps customers spot impersonators. A number lets people reply. For appointment businesses that want replies ("Reply Y to confirm"), a number is usually more useful; for one-way alerts, a sender ID works.

Cadences for the common call outcomes

Call connected, booking made

1. Immediately: confirmation with date, time, place, what to bring and how to change it.
2. Day before: reminder with a reply or link to confirm or reschedule.
3. Morning of (optional): "on the way" or arrival details for site visits.

Call not answered

1. Straight after the attempt: a short text saying who called and why, with a way to respond.
2. Later the same day, within calling hours: one more call attempt.
3. If still no answer: a final text offering a link or a number, then stop and mark the contact for human review.

Three touches is enough for someone who asked you to call. Ringing a person who isn't answering five times in a day is exactly the behaviour that makes people distrust AI callers. If the call was outbound marketing, the ACMA calling-hour and Do Not Call rules in ACMA rules for AI outbound calls apply to every attempt.

Call connected, no booking

Send a summary of what was discussed and the next step, if there is one ("Our estimator will email the quote by Friday"). If there's no next step, don't send a text at all. Silence is better than a vague nudge.

No-show

Within the hour: "We missed you today. Reply or tap here to rebook." One text, factual, no guilt. A person should decide whether to charge a cancellation fee; a machine shouldn't.

Templates you can adapt

Who approves the text?

In Fulcrum Cortex, the default is approval-first: agents draft emails and texts, and the owner approves before anything goes out. That suits marketing and anything unusual. It does slow down a confirmation that should land in seconds, so decide deliberately which message types you want to review one by one and which wording you've signed off in advance. We go into how to set those gates in human-in-the-loop approvals.

Whatever you choose, keep one do-not-contact flag that both calls and texts respect. A person who said "don't call me" on Tuesday shouldn't get a marketing text on Wednesday. With Fulcrum Lyre, call and SMS outcomes are logged to the same CRM record, which is what makes that possible.

Measuring post-call texts

Track reply rate, confirmation rate on reminders, no-show rate before and after reminders, and opt-outs per hundred marketing texts. A rising opt-out rate is the earliest sign you're texting too often or too loosely. For how these fit with the call metrics, see AI voice agent metrics; for the no-answer case specifically, see missed call text back. And if you're calling fresh enquiries, the timing of the first text matters as much as the call; speed to lead covers that.