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Upcoming appointment reminder via WhatsApp API

The scenario sends the client a personalised WhatsApp template before a scheduled visit.

Use case overview

The scenario sends the client a personalised WhatsApp template before a scheduled visit. The message includes the client name, service name, visit date, and visit time. A static URL button opens booking details.

Template example

Hello, {{1}}! Reminder: your appointment for {{2}} is on {{3}} at {{4}}. We look forward to seeing you.

View booking
  • {{1}}
    customer name
  • {{2}}
    service or appointment type
  • {{3}}
    visit date
  • {{4}}
    visit time
  • “View booking”
    button — fixed in the Meta template
WhatsApp Business API for upcoming visit reminder

When to use it

Reach for this scenario when a scheduled visit is approaching and the client needs a timely nudge before the appointment — not at booking time, but as the date draws near and email or SMS reminders are easy to miss. It fits clinics and salons with appointment schedules, field service teams where a missed slot leaves idle staff, and integrators wiring reminder jobs from scheduling systems to WhatsApp templates.

Fewer no-shows
Four body variables carry the client's name, service, visit date and time into their WhatsApp chat before the appointment, so the reminder stays visible in a channel they already check instead of buried in email.
Less rescheduling overhead
The scheduling system fires the template when it detects an approaching visit, so staff are not chasing confirmations or retyping booking details by hand.
Booking details without a reply
A static URL button fixed in the Meta template opens the booking page, so the client can view or manage the appointment without starting a WhatsApp conversation.
Reminders when no chat is open
Because the client has not opened a WhatsApp conversation, only an approved template can reach them — the send goes out as a personalised utility template rather than a free-text message Meta would block.
Delivery logged for the CRM
Delivery result is written back to the scheduling system or CRM, so reminder status sits on the same booking record that triggered the send.

Workflow

  1. Trigger

    The scheduling system detects an approaching visit and fires a reminder event.

    event · triggered

  2. Capture event

    The system resolves the client phone number and booking 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 open booking details via the button.

    delivered

  5. Status tracked

    Delivery result is logged for the scheduling system or CRM.

    status: "read"

WhatsApp Business API for upcoming 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_BOOKINGTIME="___"         # {{4}} booking time

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=$TEST_BOOKINGDATE" \
            "TEST_BOOKINGTIME=$TEST_BOOKINGTIME"; 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}} booking time → ${TEST_BOOKINGTIME}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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_BOOKINGTIME}" }
      ]
    }

  ]
}
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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