SMS appointment reminders: cost, law and setup

On 29 September 2026 Slotsy started sending SMS to clients. I decided that by default only the reminder one hour before the visit goes out by SMS, and the studio turns on the rest itself. The first test SMS to a Polish number arrived the same day. In the studio where Slotsy started, most client numbers are Ukrainian (+380), so the state of Ukrainian numbers concerns me directly.

A client books in the evening and gets a confirmation email. Nothing else happens before the visit unless she checks her calendar. The SMS an hour before is set up once; what is left is to count how many SMS you need a month and what they cost in your system.

Short answer. One SMS an hour before the visit, alongside the email, is the simplest thing you can do against no-shows: in the research, reminders cut them by about a quarter. A reminder about an appointment the client booked herself does not need marketing consent; you need it once you add a promotion. Booksy gives the most SMS with no extra charge (its system reminders are always free), Fresha includes 50 a month, and in Slotsy SMS come with paid plans: from 70 credits on Start, where an SMS to a Polish number costs 2 credits. As of 29.09.2026, SMS from Slotsy reach Polish numbers; Ukrainian ones not yet.

Create a Free account: 0 zł, no card; email reminders from the first booking, SMS from the Start plan.

Does SMS work better than email

The Cochrane review from 2013 worked this out across 7 trials and 5,841 people: an SMS reminder raises attendance with a risk ratio of 1.14 (95% CI 1.03-1.26) versus no reminder, and against a phone call gives the same effect, risk ratio 0.99. In the BMJ Open 2016 meta-analysis, no-shows fell from 21% to 15% where a reminder was sent, and several reminders worked better than one. Both reviews are about clinics and hospitals, not salons: the direction of the effect most likely carries over, but the exact percentage for your salon is something you learn only once you measure it yourself. The full numbers and the złoty calculation are in a separate article on cutting no-shows.

SMS works as well as a phone call and costs less; SMS and email were not compared in the research, so the safest thing is to send both.

An email the day before gives the client time to cancel and free up the slot for someone else. An SMS an hour before is read on the way, when cancelling would not change anything anymore, but it reminds her to leave the house. Two different moments, not one duplicated: that is why they make sense side by side, not instead of each other.

How many SMS your salon needs

The calculation is simple: visits a month times SMS per visit. One SMS per visit is just the hour-before reminder; at 120 visits a month, that is 120 SMS. Add the day-before reminder too and you multiply by two: at the same 120 visits, that is 240.

In Slotsy, SMS are counted in credits, not units: an SMS to a Ukrainian number is 1 credit, to a Polish number or any other country, 2 credits. The table below shows how many reminders (one SMS per visit) each plan covers before that month's credits run out.

With Polish clients, Start covers 35 visits a month by SMS; the rest still get the email, since that goes out regardless of the credit balance. Once credits run out, SMS stop and emails keep going without interruption: a client is never left with no reminder at all, only without this one extra one.

What SMS costs in Booksy, Fresha and Slotsy

On SMS reminders, Booksy is the most generous: its system SMS are always free.

Booksy Biz states outright that automatic appointment reminders are always free, however many you send; the subscription is 145 zł net a month, and separately 100 marketing SMS are included, then 0.10 zł net each. Fresha includes automatic reminders in both plans, plus 50 SMS or WhatsApp messages a month included (50 per employee on the Team plan), then 0.10 zł per SMS or 0.45-1.30 zł per WhatsApp message; the subscription is 29 zł net on the Individual plan, or 19 zł net per employee on the Team plan. Slotsy has no separate free pool: SMS only come with paid plans, 70/200/400 credits a month depending on the plan, and an SMS to a Polish number costs 2 credits.

So: if an SMS before every visit is a condition for you and your clients have Polish numbers, Booksy gives you the most of them for the price; Slotsy if an email twice plus an SMS an hour before the visit, within your plan's limit, is enough, and 0 zł to start, booking with no account, and a page in three languages matter more to you. Detailed comparisons: Slotsy vs Booksy, Slotsy vs Fresha.

Do you need consent for an SMS reminder

For a reminder about a booked appointment, no; for an SMS with a promotion, yes, and a separate, prior one.

Prawo komunikacji elektronicznej, art. 398(1), forbids sending commercial information, including direct marketing, to a subscriber or end user through a telecommunications terminal device or an automatic calling system without their prior consent; the rule has been in force since 10 November 2024. Art. 398(4) of the same act adds that sending it without consent is an act of unfair competition.

A reminder about an appointment the client booked herself is not commercial information: it concerns the contract she entered into, and you process her phone number to perform that contract (RODO/GDPR art. 6(1)(b)). Consent under art. 398 PKE is needed when the same SMS also carries a promotion, a discount, or an invitation to another service; then the message becomes commercial information. Check the details with a lawyer.

Practical rule: keep the reminder plain, date, time, service, salon name, nothing else. In Slotsy the SMS text is fixed anyway and nothing can be added to it, so this mistake is hard to make by accident.

How to turn on SMS in Slotsy: 5 steps

On the Start plan and above, the one-hour SMS reminder is on from the start. Before you rely on it, check these four things.

1. A paid plan (Start or higher). On Free only emails go out; SMS needs a paid plan. See plans.
2. Settings → Notifications → "SMS to customers". Check that "Reminder one hour before" is on; it is by default. Turn on "one day before" only if your clients book far ahead; the other events (confirmation, approval, decline, reschedule, cancellation) are optional and off by default. Notifications.
3. Phone numbers. SMS only goes to clients who gave a number; for visits you enter yourself, remember to fill that field in. Managing bookings.
4. Short names. A salon or service name of about a dozen characters has a better chance of fitting inside the one-segment limit intact. Managing services.
5. SMS credits. Near the end of the month, check the "SMS credits" card on "My Subscription" to see what is left. Add-ons and SMS credits.

What an SMS looks like and why it is this short

Every SMS from Slotsy is exactly one segment: 160 characters without Polish letters, 70 with them. The limit comes from SMS technology itself: one credit counts as one segment, and a segment is 160 characters when the message has no Polish or Cyrillic letters, and only 70 characters when it does, since the different encoding cuts the available space by more than half. If the text does not fit, Slotsy shortens the service name first, then the salon name; the date and time are never cut. You do not edit the SMS text: it is fixed, sent in the salon's name, with "Slotsy" as the sender. A client can turn SMS off in her own account at any time; then she gets email only.

Example text: "Pilates Zabłocie: reminder - Pilates on 01.10 at 18:30." One line: salon name, then service, date and time.

Status as of 29.09.2026: SMS from Slotsy reach Polish numbers (+48). To Ukrainian numbers (+380), SMS do not go out yet: the sender name is waiting for operator approval. Until then, a client with a +380 number gets email only, and no credit is spent.

Five mistakes

1. A promotion inside a reminder, which turns it into commercial information under art. 398 PKE and requires separate consent.
2. SMS instead of email, rather than alongside it: email goes out on every plan, always; SMS adds to it, not replaces it.
3. A day-before SMS for everyone, which doubles credit use and burns through the plan's limit faster.
4. Long salon or service names that Slotsy has to shorten to fit one segment.
5. Not counting visits against the plan's credits, then finding out at the end of the month that SMS stopped going out.

Frequently asked questions

Are SMS reminders free in Slotsy? Not on the Free plan, where only emails work. On paid plans, SMS run on credits: 70 a month on Start, 200 on Team, 400 on Business.

Why does an SMS to a Polish number cost 2 credits? That is the credit rule in Slotsy: 1 credit for an SMS to a Ukrainian number, 2 credits for an SMS to a Polish number or any other country.

Can I change the SMS text? No. The text is fixed, one line, sent in the salon's name; it cannot be edited.

Do I need the client's consent? Not for a reminder about her own booked appointment; the basis is performing the contract (RODO art. 6(1)(b)). Yes, if the message carries a promotion, which then needs separate consent under art. 398 PKE.

What happens when credits run out? SMS stop going out, emails keep going as before. Additional credit packs are not on sale yet; today you have the credits from your plan.

Will an SMS reach a Ukrainian number? As of 29.09.2026, not yet. The client gets an email, and no credit is spent.

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Prices, rules and features checked 29.09.2026. If something has changed, tell us and we will correct it and show the date of the update.

Create a Free account: 0 zł, no card, alongside your current system; email reminders from the first booking, SMS from the Start plan.