WhatsApp Business API for payment method clarification
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}}:
- {{1}}customer name
- {{2}}payment amount
- “Card”button — fixed in the Meta template“Bank Transfer”button — fixed in the Meta template

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.
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.
{
"sent": true,
"id": "wamid.HBgLMzgwNjM5...",
"message": "Message accepted for delivery"
}sentAccepted for sending — not yet on the customer's phone
idStore it; delivery callbacks and
hookInfoare keyed on this
Delivery itself arrives later, as a separate callback. Register a webhook (POST …/webhook) and 1MSG POSTs status updates to your HTTPS endpoint in a top-level hooks[] payload.
{
"hooks": [
{
"id": "gBGGeSaGViBfAgnlzOSHEwK9O6F",
"type": "message",
"status": "sent",
"timestamp": "1654864094",
"recipient_id": "556123122026"
}
]
}statussent,delivered,read— or a failure status when applicableidCorrelates the callback with the
idreturned by the send calltimestampUnix seconds, as a string
If you would rather not receive callbacks, poll GET {base}/{channel}/hookInfo?messageId=<id> instead. In practice delivery often completes within seconds — but the API contract does not guarantee it, so never block a flow waiting on it.
Common errors
| Status | Response | Cause |
|---|---|---|
| 200 | Message was not sent: template is not defined | namespace, template or language missing from the request body. |
| 200 | template name (…) does not exist in <language> | The template is approved in a different language than the one requested. |
| 200 | Message was not sent: provide chatId, phone, bsuid, or username | No recipient the channel could resolve. |
| 403 | access denied | The token is wrong, or belongs to a different channel than the URL. |
| 429 | too many requests. please try later | The channel is over its send rate. |

