Home / Dental practices / Win-back text

Recall texts for patients overdue for a cleaning

Hundreds of patients haven't been in for over a year. Nobody has time to call down the list.

⏱ Setup: 1-2 hours📶 Beginner🧩 n8n workflow
See the full setupGet the ready-to-import template

How it works

  1. Export your recall list (name, phone, last visit) to a Google Sheet. Only include patients who agreed to texts.
  2. Every morning at 10, the workflow texts anyone 180+ days past their last visit (you set the number) who hasn't been texted since, up to a daily cap.
  3. The text only says they're due and links to booking. No treatment details.
  4. Replies come to the front desk email. If someone replies with the word URGENT, the office cell gets a text right away, they get a quick 'got it', and the normal reply is skipped.
  5. The reply webhook gets the Twilio signature check (403 if not from Twilio).

Tools used

Twilio n8n Google Sheets

Realistic monthly cost≈ $6.34 + €20/mo
How we got this number
  • Twilio local number (skip if you already have one for another recipe)$1.15
  • Texting registration (A2P 10DLC) monthly fee$2
  • ~240 text segments (~200 recall texts plus replies)$1.99
  • carrier fees on ~240 outbound texts$1.20
  • Automation platform (or self-host n8n free)€20
  • Google Sheet recall list$0

Assumes ~200 recall texts a month. See the HIPAA note above before you start. Prices are list prices checked 2026-10-26; see every source.

Plus one-time texting registration (A2P 10DLC): about $19.50 (low-volume brand + campaign vetting). Source

The full setup, step by step

19 steps in one n8n workflow. Everything below is generated from the template itself, so it always matches.

Before you start

You need an n8n account (n8n, or self-host it free) plus your own logins for: Google Sheets Twilio Gmail / Google Workspace.

How the automation flows

Every morning at 10 (win-back texts)

1Every morning3Config (edit me)4Scheduled run or text?scheduled5Read your list6Due for a nudge?if yes7Daily cap8Send the win-back text9Mark as texted10Email you a summary

When someone texts you

2Incoming text3Config (edit me)4Scheduled run or text?text11Check Twilio signature12Signature valid?
if yes
13Acknowledge Twilio (text)14Says URGENT?
if yes
15Text the owner (URGENT)16Text the customer (URGENT ack)17Email the owner (URGENT, optional)
if no
18Forward the reply to you
if no
19Reject: not from Twilio (403)

Tap a step to jump to its details.

Each step and what it does

  1. 1
    Trigger (schedule)

    Every morning

    Runs on its own every morning at 10 (your n8n instance's time zone).

    Runsevery day at 10:00

    Then → 3. Config (edit me)

  2. 2
    Trigger

    Incoming text

    Twilio calls this webhook every time someone texts your business number.

    Webhook pathYOUR_N8N_URL/webhook/win-back-sms

    Then → 3. Config (edit me)

  3. 3
    Settings

    Config (edit me)

    One place for everything specific to your business. Every later step reads from here, so this is the only node you have to edit.

    Editthe settings table below

    Then → 4. Scheduled run or text?

  4. 4
    Decision

    Scheduled run or text?

    The schedule and Twilio share this workflow. Scheduled runs do the sending; texts (which carry a Twilio MessageSid) go through the signature check.

    Rulethe request has no Twilio MessageSid (so it's the scheduled run)

    Scheduled runs → 5. Read your list · Texts → 11. Check Twilio signature

  5. 5
    Google Sheets

    Read your list

    Reads every row of your Google Sheet list.

    Sheet tabRecall

    🔑 Connect your Google Sheets login on this node

    Then → 6. Due for a nudge?

  6. 6
    Decision

    Due for a nudge?

    Keeps rows with a phone, not opted out, last visit at least the number of days you set, and not already texted since that visit.

    Rulehas a phone, isn't opted out, last visit was at least winback_days ago, and hasn't been texted since that visit

    If yes → 7. Daily cap · If no → stops here

  7. 7
    Limit

    Daily cap

    Sends to at most this many people per morning (daily_cap), so replies don't flood you.

    Maxdaily_cap from Config (default 25)

    Then → 8. Send the win-back text

  8. 8
    Send SMS (Twilio)

    Send the win-back text

    Texts each person your booking link, using their first name.

    Sendsthe message shown under Message copy

    🔑 Connect your Twilio login on this node

    Then → 9. Mark as texted

  9. 9
    Google Sheets

    Mark as texted

    Writes today's date into last_texted (matched by phone) so they aren't texted again until their next visit.

    Sheet tabRecall

    🔑 Connect your Google Sheets login on this node

    Then → 10. Email you a summary

  10. 10
    Send email (Gmail)

    Email you a summary

    One email with how many texts went out today.

    Sendsthe message shown under Message copy

    🔑 Connect your Gmail login on this node

    End of this path.

  11. 11
    Code (security check)

    Check Twilio signature

    Proves the request really came from Twilio. It rebuilds Twilio's signature (HMAC-SHA1 of your webhook URL plus every field Twilio sent, keyed with your auth token) and compares it to the X-Twilio-Signature header. Uses Node's built-in crypto module: fine on n8n Cloud; self-hosted n8n needs NODE_FUNCTION_ALLOW_BUILTIN=crypto.

    DetailsHow the Twilio security check works

    Then → 12. Signature valid?

  12. 12
    Decision

    Signature valid?

    Only real Twilio requests continue. Anything else (a bot, a fake request, a wrong URL in Config) goes to the 403 step.

    Rulethe signature Twilio sent matches the one rebuilt from your auth token

    If yes → 13. Acknowledge Twilio (text) · If no → 19. Reject: not from Twilio (403)

  13. 13
    Reply to request

    Acknowledge Twilio (text)

    Tells Twilio the text was received. The reply goes out separately, so this one sends nothing to the customer.

    Then → 14. Says URGENT?

  14. 14
    Decision

    Says URGENT?

    If the customer's text contains the word URGENT (any capitalization), the urgent path runs instead of the normal reply.

    Ruletheir text contains “urgent”

    If yes → 15. Text the owner (URGENT) · If no → 18. Forward the reply to you

  15. 15
    Send SMS (Twilio)

    Text the owner (URGENT)

    Texts your cell right away with their number and exactly what they wrote.

    Sendsthe message shown under Message copy

    🔑 Connect your Twilio login on this node

    Then → 16. Text the customer (URGENT ack)

  16. 16
    Send SMS (Twilio)

    Text the customer (URGENT ack)

    Lets the customer know their message reached you.

    Sendsthe message shown under Message copy

    🔑 Connect your Twilio login on this node

    Then → 17. Email the owner (URGENT, optional)

  17. 17
    Send email (Gmail)

    Email the owner (URGENT, optional)

    A copy by email. If Gmail isn't connected or fails, the workflow still finishes (the text already went out).

    Sendsthe message shown under Message copy

    🔑 Connect your Gmail login on this node

    End of this path.

  18. 18
    Send email (Gmail)

    Forward the reply to you

    Emails you what they wrote, so you can answer from your phone.

    Sendsthe message shown under Message copy

    🔑 Connect your Gmail login on this node

    End of this path.

  19. 19
    Reply to request

    Reject: not from Twilio (403)

    Answers 403 Forbidden and stops. Nothing is texted, emailed or saved.

    Responds403 Forbidden

    End of this path.

Key settings to change

All of these live in the Config (edit me) node. Change them once and every text and email updates.

SettingPlaceholder in the templateChange it to
Business name
business_name		YOUR BUSINESS NAMEExactly how customers know you. It appears in every text.
Booking / calendar link
booking_link		https://YOUR-BOOKING-LINKYour online booking page (Calendly, your CRM's scheduler, or your contact page). Use the short public link.
Hours
hours		Mon-Fri 8am-6pmShort and text-friendly, e.g. Mon-Fri 8am-6pm.
Your email
owner_email		you@example.comWhere the 'new lead' and 'missed call' alerts go.
Your cell
owner_cell		+15555550100In +1 format (+15551234567).
Twilio number
twilio_number		+15555550199The number you bought in Twilio, in +1 format. Texts are sent from it.
Twilio auth token
twilio_auth_token		PASTE_YOUR_TWILIO_AUTH_TOKENTwilio Console > Account info > Auth Token. Used only to check that requests really came from Twilio. Treat it like a password: don't share the workflow once it's filled in.
Incoming-text webhook URL
twilio_sms_webhook_url		https://YOUR-N8N-URL/webhook/win-back-smsThe exact Production URL of the Incoming text node, the same one you paste into Twilio (Messaging > A message comes in). One character off and every text gets a 403.
List Google Sheet ID
clients_sheet_id		YOUR_GOOGLE_SHEET_IDThe long code in the sheet's URL between /d/ and /edit.
Days until a nudge
winback_days		180How many days after the last visit (or last contact) someone gets the text.
Daily cap
daily_cap		25The most texts sent in one morning.

Message copy: exactly what it sends

Highlighted parts are filled in automatically. Edit the wording right in the node.

SMS to [their phone] · step 8
Hi their first name, it's business name. You're due for your next cleaning and checkup. Book a time here: booking link or reply and we'll call you. Reply STOP to opt out.
Email to [your email] · step 10

Subject Win-back texts sent today: number sent

Texted number sent people from your list today. Replies come to you by email; anyone who replies STOP is opted out by Twilio automatically (also put an x in their opted_out cell).
SMS to [your cell] · step 15
URGENT text to business name from their phone number: "their text" Call or text them back now.
SMS to [their phone number] · step 16
Got it, we've flagged this for our team and someone will call you as soon as possible. If you have swelling that's spreading, trouble breathing or swallowing, or bleeding that won't stop, call 911. - business name
Email to [your email] · step 17

Subject URGENT: text from their phone number

They wrote: their text

Your cell was texted and they were told you'll get back to them right away.
Email to [your email] · step 18

Subject Reply from their phone number (replied to a win-back text)

They wrote: their text

Reply to them from your phone or the Twilio console.

How the Twilio security check works

Your webhook URL is public, so anyone who finds it could send fake "texts" and make the workflow text people on your dime. Every request Twilio sends is signed, so the first thing this workflow does is check that signature:

  1. Take the exact webhook URL from Config (twilio_sms_webhook_url, or twilio_voice_webhook_url for call events).
  2. Sort every field Twilio posted by name and glue each name and value onto the end of the URL (…BodyhiFrom+1555…).
  3. HMAC-SHA1 that string with your Twilio auth token, base64-encode it, and compare it to the X-Twilio-Signature header (a constant-time compare).
  4. Match: continue. No match, no header, or no URL/token in Config: answer 403 Forbidden and stop.

It's a Code node because n8n's Crypto node can't do HMAC-SHA1. It uses Node's built-in crypto module: allowed on n8n Cloud. Self-hosted n8n: set the environment variable NODE_FUNCTION_ALLOW_BUILTIN=crypto (on your task runners too, if you use them), or the node errors.

The auth token lives only in Config. Never paste it into the code, and don't share your workflow export once it's filled in.

Hook it up

  1. Make a Google Sheet with a tab named Recall and columns name | phone | last_visit | last_texted | opted_out. Phones in +1 format, dates as YYYY-MM-DD (format the columns as plain text). Most practice-management systems can export a recall list to a spreadsheet; keep only name, phone and last visit.
  2. Fill in Config (edit me): sheet ID, how many days counts as overdue (winback_days), the daily cap, Twilio number, auth token and webhook URL.
  3. Connect Google Sheets, Twilio and Gmail credentials.
  4. In Twilio > Phone Numbers > your number > Messaging: 'A message comes in' > Webhook, HTTP POST, https://YOUR-N8N-URL/webhook/win-back-sms. Paste the exact same URL into twilio_sms_webhook_url in Config. A number has one 'message comes in' webhook, so if you run several of these workflows on one number, point it at only one of them.
  5. Only include people who agreed to get texts from you. Activate: every morning at 10 it texts up to the daily cap, once per visit.

Security: the Check Twilio signature node rejects (403) anything not signed with your Twilio auth token. Self-hosted n8n: set NODE_FUNCTION_ALLOW_BUILTIN=crypto. Don't share this workflow once your token is in it.

Test it before you trust it

Skip the clicking

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