💬 Shared WhatsApp Inbox on the new PlatformMore
1msg official logo

Appointment reminder days ahead via WhatsApp API

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

Use case overview

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

Template example

Hello, {{1}}! Reminder: your appointment for {{2}} is on {{3}} at {{4}}. Please plan ahead — we look forward to seeing you.

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

When to use it

Reach for this scenario when an appointment was booked days or weeks ahead and the business needs the client to remember it well before the visit — not only on the morning of. It fits clinics and salons with sparse calendars, long-lead bookings where a missed slot costs a paid hour, and integrators wiring scheduling reminder rules into WhatsApp outbound.

Fewer no-shows on long-lead bookings
When the scheduling system detects an appointment several days away, it sends four body variables — name, service, date and time — so the visit stays on the client's radar before the day-of rush.
Details that survive email overload
The reminder lands in WhatsApp with every booking field in the message body, so the client can search the chat instead of digging through inbox threads from weeks ago.
No manual reminder chasing
The scheduling rule fires the approved template on the reminder event, resolves phone and booking fields, and logs delivery — no staff retyping dates or copying links.
Booking access without a reply
The static URL button fixed in the Meta template opens booking details from the reminder itself, so the client does not need to message back inside the 24-hour window.

Workflow

  1. Trigger

    The scheduling system detects an appointment several days away 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 scheduling or CRM follow-up.

    status: "read"

WhatsApp Business API for advance booking 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

Build for WhatsApp in hours
without infrastructure hassle