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Reschedule confirmation via WhatsApp API

The scenario sends the client a personalised WhatsApp template when a booking is rescheduled.

Use case overview

The scenario sends the client a personalised WhatsApp template when a booking is rescheduled. The message includes the client name, service name, new date, and new time. A static URL button opens booking details.

Template example

Hello, {{1}}! Your {{2}} appointment has been rescheduled to {{3}} at {{4}}.

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

When to use it

Reach for this scenario when a client or staff member moves an appointment and the business needs the new date and time confirmed somewhere the client will actually see it. It fits salons and clinics where schedule changes are common, restaurants rebooking tables on WhatsApp, and integrators wiring reschedule webhooks from a scheduling system or CRM.

Fewer no-shows after a reschedule
Name, service, new date and new time arrive as four body variables in the client's WhatsApp chat, so the updated slot stays searchable there instead of buried in an email about the old appointment.
Less old-vs-new slot confusion
The template names the service and states the new date and time in one message, so the client is not left guessing whether the original booking or the moved slot still applies.
No manual reconfirmation work
The scheduling system fires the template on the reschedule event with the new booking fields, so no one retypes the details or remembers to send a follow-up message.
Clearer reschedule audit trail
Delivery result is logged back to the scheduling system or CRM on send, so staff can see the client received the new time without checking WhatsApp manually.

Workflow

  1. Customer acts

    Client or staff completes a reschedule and the system fires an event.

    user action

  2. Capture event

    The system resolves the client phone number and new 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 confirmation with the new date and time.

    delivered

  5. Status tracked

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

    status: "read"

WhatsApp Business API for booking reschedule confirmation

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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