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Follow-up visit reminder via WhatsApp API

The scenario sends the client a personalised WhatsApp template when a follow-up or repeat visit is due.

Use case overview

The scenario sends the client a personalised WhatsApp template when a follow-up or repeat visit is due. The message includes the client name, service, relevant date, and next step. A static URL button opens rebooking.

Template example

Hello, {{1}}! It is time for your follow-up {{2}} around {{3}}. Next step: {{4}}

Book again
  • {{1}}
    customer name
  • {{2}}
    service or visit type
  • {{3}}
    follow-up or recommended date
  • {{4}}
    recommended next step
  • “Book again”
    button — fixed in the Meta template
WhatsApp Business API for follow-up visit reminder

When to use it

Reach for this scenario when a completed visit should lead to the next appointment — maintenance, check-ups, or recurring care — but the client has no open WhatsApp thread and only an approved template can start the conversation. It fits healthcare practices reminding patients about follow-up check-ups, maintenance businesses nudging recurring service visits, and integrators connecting CRM follow-up rules to WhatsApp outbound.

More repeat bookings from past clients
The scheduling system or CRM fires the template when a follow-up visit is due, so the reminder reaches clients who already used the service instead of slipping off a manual outreach list.
Fewer forgotten follow-up visits
Four body variables carry the client name, service type, recommended date, and next-step text in their WhatsApp chat, so the follow-up details stay visible instead of buried in email.
Rebooking without a back-and-forth chat
A static URL button fixed in the Meta template opens the booking page directly, so the client can schedule again without replying in WhatsApp.
No manual follow-up chasing
Follow-up fields are resolved from the scheduling system on the reminder event, so no one retypes names, services, or dates for each due client.
Delivery logged for CRM follow-up
The send result is written back to the scheduling system or CRM, so repeat-booking workflows report on the same record that triggered the reminder.

Workflow

  1. Trigger

    The scheduling system or CRM fires a follow-up visit reminder event.

    event · triggered

  2. Capture event

    The system resolves the client phone number and follow-up fields.

    phone: "+…"

  3. Build & send

    A personalised template message is built with four body variables and a static URL button.

    POST /sendTemplate

  4. Delivered

    The client receives the WhatsApp reminder and can book again via the button.

    delivered

  5. Status tracked

    Delivery result is logged for scheduling or CRM follow-up.

    status: "read"

WhatsApp Business API for follow-up visit reminder

Technical implementation

Prerequisites

  1. 1MSG API Key · How to get API Key
  2. WhatsApp Business account · How to Connect WABA
  3. WhatsApp Template · How to Approve WABA Template
  4. Customer opt-in · How to Manage Customers Consent

Code examples

#!/usr/bin/env bash
set -euo pipefail

# === Configuration (replace "___" placeholders) ===

API_BASE_URL="https://api.1msg.io"        # production 1MSG API base URL
CHANNEL_ID="___"                           # channel ID from 1MSG dashboard
API_TOKEN="___"                            # channel JWT token (Bearer)

TEMPLATE_NAME="___"                        # approved template name
TEMPLATE_NAMESPACE="___"                   # template namespace (required — send fails without it)
TEMPLATE_LANGUAGE="___"                    # template language code, e.g. "en"



# === Test data ===
TEST_PHONE="___"                 # client phone in international format
TEST_CUSTOMERNAME="___"         # {{1}} customer name
TEST_SERVICE="___"         # {{2}} service name
TEST_BOOKINGDATE="___"         # {{3}} booking date
TEST_NEXTSTEP="___"         # {{4}} next step

PHONE_NORM="$(printf '%s' "$TEST_PHONE" | tr -cd '0-9')"

for pair in "CHANNEL_ID=$CHANNEL_ID" "API_TOKEN=$API_TOKEN" \
            "TEMPLATE_NAME=$TEMPLATE_NAME" "TEMPLATE_NAMESPACE=$TEMPLATE_NAMESPACE" \
            "TEMPLATE_LANGUAGE=$TEMPLATE_LANGUAGE" "TEST_PHONE=$TEST_PHONE" \
            "TEST_CUSTOMERNAME=$TEST_CUSTOMERNAME" \
            "TEST_SERVICE=$TEST_SERVICE" \
            "TEST_BOOKINGDATE=$TEST_BOOKINGDATE" \
            "TEST_NEXTSTEP=$TEST_NEXTSTEP"; do
    val="${pair#*=}"
    if [ -z "$val" ] || [ "$val" = "___" ]; then
        echo "Missing configuration value: ${pair%%=*}" >&2
        exit 1
    fi
done

if [ -z "$PHONE_NORM" ]; then
    echo "Error: phone number has no digits after normalization" >&2
    exit 1
fi

URL="${API_BASE_URL%/}/${CHANNEL_ID}/sendTemplate"

# params carries body ONLY. Button text is fixed in the Meta template — no button param.

# {{1}} customer name → ${TEST_CUSTOMERNAME}
# {{2}} service name → ${TEST_SERVICE}
# {{3}} booking date → ${TEST_BOOKINGDATE}
# {{4}} next step → ${TEST_NEXTSTEP}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${PHONE_NORM}",
  "template": "${TEMPLATE_NAME}",
  "namespace": "${TEMPLATE_NAMESPACE}",
  "language": { "policy": "deterministic", "code": "${TEMPLATE_LANGUAGE}" },
  "params": [
    {
      "type": "body",
      "parameters": [
        { "type": "text", "text": "${TEST_CUSTOMERNAME}" },
        { "type": "text", "text": "${TEST_SERVICE}" },
        { "type": "text", "text": "${TEST_BOOKINGDATE}" },
        { "type": "text", "text": "${TEST_NEXTSTEP}" }
      ]
    }

  ]
}
JSON

RESPONSE="$(curl -s -w '\n%{http_code}' -X POST "$URL" \
    -H "Content-Type: application/json" \
    -H "Authorization: Bearer ${API_TOKEN}" \
    -d "$PAYLOAD")"

HTTP_CODE="$(printf '%s' "$RESPONSE" | tail -n1)"
BODY="$(printf '%s' "$RESPONSE" | sed '$d')"

case "$BODY" in
    *'"sent":true'*) ok=1 ;;
    *) ok=0 ;;
esac

if [ "$HTTP_CODE" -ge 200 ] && [ "$HTTP_CODE" -lt 300 ] && [ "$ok" -eq 1 ]; then
    echo "Message sent to client."
    echo "API response: $BODY"
else
    echo "Send failed. HTTP status: $HTTP_CODE" >&2
    echo "$BODY" >&2
    exit 1
fi

Response and delivery status

HTTP 2xx and JSON "sent": true mean 1MSG accepted the message for sending — not that it already reached the customer's phone. Save the id field (looks like wamid.…) to correlate delivery callbacks.

200 OKResponse
{
  "sent": true,
  "message": "Sent to [email protected]",
  "description": "Message has been sent to the provider",
  "id": "wamid.HBgLMzgwNjM5..."
}
  • sent

    Accepted for sending — not yet on the customer's phone

  • id

    Store it; delivery callbacks and hookInfo are keyed on this

Delivery statuses and webhooks →

Common errors

StatusAPI responseCauseFix
200Message was not sent: template is not definednamespace, template or language is missing from the request body.Send all three. Take namespace and the exact template name from GET /templates; language is an object: {"policy": "deterministic", "code": "en"}.
200template name (…) does not exist in <language>The template is approved in a different language than the one requested.Use the exact language code the template was approved in (for example es_MX is not the same as es). Check it in GET /templates.
200Message was not sent: provide chatId, phone, bsuid, or usernameNo recipient the channel could resolve.Pass exactly one recipient: phone (country code plus number, digits only), chatId (for example [email protected]) or bsuid.

All error codes →

Common questions

Related

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