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Service change notification via WhatsApp API

The scenario sends the client a personalised WhatsApp template when the business changes how a service or process runs for them.

Use case overview

The scenario sends the client a personalised WhatsApp template when the business changes how a service or process runs for them. The message includes the client name, the service or process affected, and a short summary of what changed. A static URL button opens the portal or details page.

Template example

Hello, {{1}}! The status of your {{2}} has been updated. {{3}} If you need help — we are here.

Learn more
  • {{1}}
    customer name
  • {{2}}
    service or process (e.g. home delivery, onboarding, maintenance visit)
  • {{3}}
    change summary (e.g. new date 25 June 10:00–12:00, added document upload step)
  • “Learn more”
    button — fixed in the Meta template
WhatsApp Business API for service process change notification

When to use it

Reach for this when an ongoing service or multi-step process changes for a client — a rescheduled delivery window, updated onboarding steps, revised plan terms — and they may have no open WhatsApp conversation, so only an approved template can reach them first. It fits logistics and field service teams adjusting visit schedules, subscription and SaaS businesses changing onboarding or plan terms, and agencies connecting CRM or BPM process-updated events to WhatsApp outbound.

Fewer support calls about what changed
Three body variables carry the client name, the affected service or process, and a short change summary in WhatsApp, so the update stays in a chat they already check instead of an email or portal login.
Fewer missed appointments and delivery windows
When a visit or delivery window moves, the change summary goes out the moment the back office, CRM, or integration emits the service or process change event, so the client sees the new slot before the old one passes.
Proactive reach outside the 24-hour window
An approved utility template can start the conversation when there is no active session, which free-text session messages cannot do after the window closes.
Self-service follow-up from one tap
A static URL button fixed in the Meta template opens the portal or details page for anything the summary does not cover, while only the three body variables are sent via the API.
Traceable delivery for CRM follow-up
Delivery result is logged after send, so back-office or integration workflows can handle errors and attach the notification to the same client record that triggered the change event.

Workflow

  1. Trigger

    The back office, CRM, or integration emits a service/process change event.

    event · triggered

  2. Capture event

    The system resolves the recipient phone number and change fields.

    phone: "+…"

  3. Build & send

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

    POST /sendTemplate

  4. Delivered

    The client receives the WhatsApp notification with the change summary.

    delivered

  5. Status tracked

    Delivery result is logged; errors are handled according to platform rules.

    status: "read"

WhatsApp Business API for service process change notification

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_DETAILS="___"         # {{3}} change details

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_DETAILS=$TEST_DETAILS"; do
    val="${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}} change details → ${TEST_DETAILS}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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_DETAILS}" }
      ]
    }

  ]
}
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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