SMS Auto Reply: How to Set It Up Properly

An SMS auto reply is a message your number sends back on its own. That sounds trivial until you run one badly: the wrong automatic text at the wrong moment reads as a business that is not listening, and unlike a DM, a text arrives on a lock screen next to messages from actual people.

What an auto reply is for

• Answering out of hours, so a message at 11pm does not sit unanswered until morning.
• Confirming you received something: a booking request, a quote enquiry, a reply to a campaign.
• Answering the question you get twenty times a day, and escalating only the ones you do not.
• Collecting one piece of information, such as an email address or an order number, before a person picks the conversation up.

What it is not for is pretending to be a person. An auto reply that opens with a chatty greeting and no information wastes the one moment you had someone's attention, and the second message rarely gets read.

How SMS differs from Instagram DMs

Two differences change how you write. The first is the 24-hour window. Instagram, Messenger and WhatsApp all limit what a business can send after the last customer message. SMS has no such window, so a follow-up three days later is technically possible. That makes restraint your job rather than the platform's, and it is the single biggest way businesses damage an SMS list.

The second is formatting. A DM can carry buttons. A text cannot. MuChat's flow builder, steps and buttons work the same on your SMS number as on Instagram, and on SMS the buttons become plain reply options, written out as Reply: Yes / Book. Links are written out in full rather than hidden behind words, because a bare URL in a text is something people can see before they tap.

Using your own number

MuChat sends SMS through your own Twilio number. You buy the number in your Twilio account and connect it, so the number is yours: it keeps working if you change tools, the sending history sits in an account you control, and the spend is visible to you directly rather than bundled into a subscription.

Twilio also handles the compliance keywords. STOP and START are processed at their end, so an opt-out is honoured whether or not your flow anticipated it. You should still write flows as though someone can leave at any point, because they can, and because a flow that ignores that possibility reads badly to the people still in it.

Writing an auto reply people do not hate

1. 01Say who it is. A text from an unknown number with no name gets deleted.
2. 02Answer something. An acknowledgement that contains no information is noise.
3. 03Set the expectation. If a human replies in the morning, say so.
4. 04Offer one next step, not four. On SMS, choice is friction.
5. 05Keep it short enough to read on a lock screen without opening it.

A useful test: read the message out loud as though you were saying it to the person across a counter. If it sounds like a form letter, it will read like one on a phone.

A worked example

A salon gets a text at 9pm asking whether there is anything on Saturday. The auto reply names the salon, says the desk opens at 9am, and offers one option: Reply: SAT to be put on the callback list for Saturday. The person replies SAT, the flow records it, and the morning starts with a list instead of a voicemail queue.

Nothing about that is clever. It works because it answers, sets a time, and asks for one thing. The version that fails says We have received your message and will get back to you, which is three sentences of nothing.

Handing over to a person

Most SMS conversations should end with a human, and the handover is where automation usually falls down. Make it explicit in the flow: when someone asks something the flow cannot answer, say a person will pick it up and then actually route it. Replies land in the same inbox as your Instagram threads, so nobody has to watch two screens: /product/inbox.

When SMS is the wrong channel

If the conversation started on Instagram, keep it on Instagram. Moving a person to SMS asks them to hand over a phone number they have not offered, and that is a real cost in trust for a small gain in convenience. SMS earns its place when the person gave you the number for this purpose: a booking, an order, a delivery.

The other case where SMS wins is reach. A text does not depend on someone opening an app, which matters for time-sensitive messages: an appointment tomorrow, a delivery today, a cancellation.

Keep a record of what was said

Texts are easy to lose track of, because each one lives on a phone rather than in a system. If an SMS conversation produces something worth keeping, an appointment, an address, a reference number, write it somewhere durable in the same flow rather than trusting that someone will copy it across later. The Send to app step will put it into HubSpot, Mailchimp, Klaviyo or a Google Sheet while the conversation is still open.

Setting it up

Connect your Twilio number in Settings, then build the automation on it in /product/flow-builder. Start with the out-of-hours case, because it is the easiest to judge: if the morning queue is shorter and nobody complains, it works. Templates to start from are in /templates.