Two-Way SMS Appointment Confirmations with VoxiSMS & n8n

Two-Way SMS appointment confirmations—automated with VoxiSMS + n8n

Send appointment reminders from your Android number, track YES/CANCEL/RESCHEDULE/STOP replies against the correct booking, and route unclear or uncertain SMS events into a staff queue—using VoxiSMS and n8n.

What this workflow does

• Updates bookings via authenticated webhooks: incoming booking webhooks update your PostgreSQL record with appointment time, timezone, phone number, consent, and source update timestamps.
• Runs on a schedule with local sending hours: every five minutes, it identifies due appointments that fall within allowed local sending hours.
• Respects consent + persistent STOP opt-outs: reminders are sent only when consent is valid, and STOP suppresses future reminders.
• Prevents duplicate sends across overlapping runs: appointments are processed one at a time, with an atomic reservation of one reminder attempt per booking revision.
• Sends authorized reminders through VoxiSMS: each reminder includes an appointment reference and a custom message ID to support reconciliation.
• Tracks acceptance separately from delivery: API acceptance is recorded independently from delivery; uncertain sends go to a staff queue and are not automatically retried.
• Handles incoming SMS with signature verification: incoming SMS signatures are verified and replies are matched by sender, receiving line, and reference.

• YES confirms the appointment.
• CANCEL and RESCHEDULE create staff requests.
• STOP suppresses future reminders.
• Ambiguous replies are queued for staff, and repeated events do not re-apply state changes.

Use cases

• Hair salons and service businesses that need reliable appointment confirmation and fast cancellation/reschedule handling.
• Operations teams wanting visibility into uncertain deliveries and unclear replies without risky automatic retries.
• SaaS operators building appointment systems that require audit-friendly SMS reconciliation via message IDs.

Technical details

• n8n nodes used: if, set, no op, webhook, postgres, sticky note
• Database: PostgreSQL 15+ with provided schema.sql
• VoxiSMS: reminder sending, reply validation via signature verification, sender/line/reference matching