How much does Twilio SMS cost after the free trial?

After the $15.50 free trial credit is used, Twilio charges per SMS sent. UK: approximately £0.04 per SMS. US: $0.0079 per SMS. India: $0.0039 per SMS. Australia: $0.054 per SMS. A business sending 100 reminders per month in the UK pays around £4/month — less than a cup of coffee. The phone number itself costs about $1/month to rent.

Can I send SMS reminders without Twilio using WhatsApp instead?

Yes — WhatsApp reminders are free and often preferred in markets where WhatsApp penetration is high (India, UK, Middle East, Africa, Latin America). Use WATI or Respond.io with Zapier instead of Twilio. The setup is similar but you use a WhatsApp template message instead of SMS. The guide's WhatsApp Booking Bot (Guide 03) covers this in detail.

What booking systems work with this SMS reminder setup?

Any booking system with a Zapier integration works: Cal.com, Calendly, Acuity Scheduling, Booksy, Vagaro, HoneyBook, Simply Book.me, and dozens more. If your system doesn't have a Zapier integration, you can use a Google Form as a manual trigger (fill it in after each booking and Zapier picks it up) — covered in Step 4.

Is sending unsolicited SMS reminders legal?

Yes, appointment reminders are legal in all major markets because the customer gave consent when they made the booking. They entered their phone number and agreed to be contacted about their appointment. This is called transactional SMS and is exempt from the marketing SMS restrictions in the UK (PECR), US (TCPA), India (TRAI), and Australia (Spam Act). You must still include a way for customers to opt out (reply STOP) and honour opt-outs immediately.

📲 Guide 10 · SMS Appointment Reminders

Customers show up.
Every time. Because
their phone told them.

Send automatic SMS reminders 24 hours before every appointment using Twilio + Zapier. Set up once, runs forever. Cuts no-shows by 70%. Costs less than £4/month after the free trial.

❌ What You're Paying

~~Appointy: $29.99/month~~

~~Acuity SMS add-on: $20/month~~

~~Podium: $399/month~~

✅ What You'll Build

Twilio: $15.50 free trial credit

After trial: ~$1–4/month (100 SMS)

Zapier free tier: 100 tasks/month

💰 Save up to $348/year vs Appointy SMS

9:41 AM📶 ●●●

‹

Glow Studio

Business · +44 7700 900123

Yesterday 2:30 PM

Hi Emma 👋 This is a reminder that your Facial Treatment is tomorrow at 10:30 AM at Glow Studio, 14 Kings Road. Reply STOP to opt out. AUTO

Message

↑

📉

No-show rate

↓ 70%

💷

Cost per 100 SMS (UK)

~£4/mo

🌍

Countries supported

180+

🔗

Part of the Booking Automation Stack This guide works best as part of a connected setup. SMS reminders plug into your booking system and feed into your review automation.

📅 Guide 06: Booking System 📲 Guide 10: SMS Reminders ← you are here ⭐ Guide 05: Auto Reviews

📱

SMS — 98% open ratevs 20% for email reminders

⚡

Twilio — 180+ countriesLocal numbers in UK, US, AU, IN, CA + more

🔄

Set up once, runs foreverNo manual sending. Ever.

🎉

Reminders are live!

Every appointment now triggers an automatic SMS reminder. No-shows are about to drop.

Save $348/year

Complete the booking automation stack:

📅

Online Booking System

Save $600/yr

⭐

Auto Google Reviews

Save $1,188/yr

✅

WhatsApp Business

Save $240/yr

Unlock AI Support

One-time $5 — Unlimited help with your SMS reminder setup. 7 days.

Twilio setup, number purchase, API credentials

Zapier flow: booking trigger → delay → SMS action

Make.com alternative setup (free 1,000 ops/month)

SMS compliance for UK, India, US, Australia

50 messages · 7 days access

Each guide has its own $5 support session.

Customers show up. Every time. Because their phone told them.

Customers show up.
Every time. Because
their phone told them.