Send invoice notifications via WhatsApp API

The scenario sends the customer a personalized WhatsApp template when a new invoice is issued.

Use case overview

The scenario sends the customer a personalized WhatsApp template when a new invoice is issued. The message includes the customer name, invoice number, amount due, and payment due date. A static URL button opens the invoice or payment page.

Template example

Hello, {{1}}! Invoice #{{2}} has been issued for {{3}}. Payment due: {{4}}.

Pay invoice

{{1}}
customer name
{{2}}
invoice number
{{3}}
amount due
{{4}}
payment due date
“Pay invoice”
button — fixed in the Meta template

WhatsApp Business API for invoice send notification

When to use it

Reach for this scenario when billing issues a new invoice and the customer expects it on WhatsApp, but there is no open chat — only an approved template can start delivery. It fits B2B billing teams, subscription and service businesses tired of lost email attachments, and integrators wiring accounting or ERP invoice-created webhooks to WhatsApp.

Fewer lost invoices

Four body variables carry the customer name, invoice number, amount due and payment due date into the client's WhatsApp chat, so the summary stays visible instead of buried in a filtered email attachment.

One-tap pay from the message

A static URL button opens the invoice or payment page fixed in the Meta template, so the client can view or pay without hunting for a link in email — only the four body variables are sent via the API.

No manual invoice delivery

Billing fires a new-invoice event, the system resolves the customer phone and invoice fields, and the template goes out automatically — no one retypes amounts or due dates for each customer.

Delivery status for billing follow-up

Delivery result is logged after send, so billing or CRM systems can track whether the invoice reached the customer and handle errors according to platform rules.

Workflow

Trigger
Billing issues a new invoice and fires an event.
event · triggered
Capture event
The system resolves the customer phone number and invoice fields.
phone: "+…"
Build & send
A personalized template message is built with four body variables and a static URL button.
POST /sendTemplate
Delivered
The customer receives the WhatsApp invoice summary and can pay via the button.
delivered
Status tracked
Delivery result is logged; errors are handled according to platform rules.
status: "read"

Technical implementation

Prerequisites

1MSG API Key · How to get API Key
WhatsApp Business account · How to Connect WABA
WhatsApp Template · How to Approve WABA Template
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_TICKETNUMBER="___"         # {{2}} ticket number
TEST_PAYMENTAMOUNT="___"         # {{3}} payment amount
TEST_DUEDATE="___"         # {{4}} due date

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=$TEST_CUSTOMERNAME" \
            "TEST_TICKETNUMBER=$TEST_TICKETNUMBER" \
            "TEST_PAYMENTAMOUNT=$TEST_PAYMENTAMOUNT" \
            "TEST_DUEDATE=$TEST_DUEDATE"; 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}} ticket number → ${TEST_TICKETNUMBER}
# {{3}} payment amount → ${TEST_PAYMENTAMOUNT}
# {{4}} due date → ${TEST_DUEDATE}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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": "${TEST_TICKETNUMBER}" },
        { "type": "text", "text": "${TEST_PAYMENTAMOUNT}" },
        { "type": "text", "text": "${TEST_DUEDATE}" }
      ]
    }

  ]
}
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

Status	API response	Cause	Fix
200	Message was not sent: template is not defined	namespace, 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"}.
200	template 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.
200	Message was not sent: provide chatId, phone, bsuid, or username	No recipient the channel could resolve.	Pass exactly one recipient: phone (country code plus number, digits only), chatId (for example [email protected]) or bsuid.