Payment method choice with WhatsApp buttons (API)

The scenario sends the customer a personalised WhatsApp template when billing needs to know the payment method.

Use case overview

The scenario sends the customer a personalised WhatsApp template when billing needs to know the payment method. The message includes the customer name and amount due. Two quick-reply buttons let the customer choose card or bank transfer; the webhook delivers the choice to your backend.

Template example

Hello, {{1}}! Please choose how you will pay {{2}}:

Card

Bank Transfer

{{1}}
customer name
{{2}}
payment amount
“Card”
button — fixed in the Meta template
“Bank Transfer”
button — fixed in the Meta template

WhatsApp Business API for payment method clarification

When to use it

Reach for this scenario when billing is ready to collect payment but the customer's method is still unknown and you need that answer before generating the right instructions — and there is no open WhatsApp session to ask in free text. It fits checkout and billing flows, B2B invoicing where card vs bank transfer changes what you send next, and integrators routing quick-reply webhook events into billing or ERP.

Correct payment instructions on first try

Customer name and amount due arrive as two body variables, and two quick-reply buttons ask card vs bank transfer; the webhook returns the tap as a structured choice billing can use for the next step.

No payment-method email ping-pong

An approved template opens the chat outside the 24-hour window, so billing can ask how they will pay in WhatsApp instead of waiting on replies buried in email.

Less manual billing follow-up

Billing fires the send when it detects a missing payment method on an invoice or checkout, so no one retypes the amount or chases the customer by phone.

ERP-ready structured answers

Card and bank transfer are fixed quick-reply labels in the Meta template; only body variables go through the API, and the inbound webhook delivers the button event to your backend for routing.

Workflow

Trigger
Billing detects that payment method is missing and fires an event.
event · triggered
Capture event
The system resolves the customer phone number and payment amount.
phone: "+…"
Build & send
A personalised template message is built with two body variables and two quick-reply buttons.
POST /sendTemplate
Delivered
The customer receives the WhatsApp message and taps card or bank transfer.
delivered
Status tracked
The webhook delivers the structured choice to billing for the next payment step.
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
Webhook endpoint · How to Set Up Webhooks

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_PAYMENTAMOUNT="___"         # {{2}} payment amount

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=$TEST_CUSTOMERNAME" \
            "TEST_PAYMENTAMOUNT=$TEST_PAYMENTAMOUNT"; 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}} payment amount → ${TEST_PAYMENTAMOUNT}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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_PAYMENTAMOUNT}" }
      ]
    }

  ]
}
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.