WhatsApp Business API for session reply — availability inquiry
This scenario sends a free-text WhatsApp message with sendMessage inside the 24-hour customer service window after the client asks if an item is available.
Use case overview
This scenario sends a free-text WhatsApp message with sendMessage inside the 24-hour customer service window after the client asks if an item is available.
Template example
Hello, {{1}}! «{{2}}» is currently {{3}}. Reply here if you want to reserve, get a restock alert, or see similar options.
- {{1}}client name
- {{2}}product or service name
- {{3}}availability status or expected date
When to use it
Reach for this when a prospect asks whether a product or service is in stock or bookable inside an open WhatsApp chat and the answer must land before they leave for a competitor. It fits sales teams pulling live inventory from OMS or CRM, developers wiring webhook-driven session replies, and agencies handling availability for client catalogs.
Workflow
- Status tracked
An inbound client message with an availability question arrives via webhook.
status:"read" - Resolves the SKU
Your backend resolves the SKU and current stock or slot status.
status:"read" - Build & send
A session text message sends the product name and availability summary.
POST/sendMessage - Delivered
The client continues the dialog to reserve or choose alternatives.
delivered
Technical implementation
Prerequisites
- 1MSG API Key · How to get API Key
- WhatsApp Business account · How to Connect WABA
- Open 24-hour session window · How the 24-hour window works
- 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)
# === Test data ===
TEST_PHONE="___" # client phone in international format · requires open 24-hour session window
TEST_CUSTOMERNAME="___" # {{1}} customer name
TEST_PRODUCTORSERVICENAME="___" # {{2}} product or service name
TEST_STATUS="___" # {{3}} status label
PHONE_NORM="$(printf '%s' "$TEST_PHONE" | tr -cd '0-9')"
for pair in "CHANNEL_ID=$CHANNEL_ID" "API_TOKEN=$API_TOKEN" "TEST_PHONE=$TEST_PHONE" \
"TEST_CUSTOMERNAME=$TEST_CUSTOMERNAME" \
"TEST_PRODUCTORSERVICENAME=$TEST_PRODUCTORSERVICENAME" \
"TEST_STATUS=$TEST_STATUS"; 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}/sendMessage"
read -r -d '' PAYLOAD <<JSON || true
{
"phone": "${PHONE_NORM}",
"body": "Hello, Alexey! «Premium Plan license» is currently in stock — ready to ship today. Reply here if you want to reserve, get a restock alert, or see similar options."
}
JSON
RESPONSE="$(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: empty body | No body in the request. |
| 200 | Message was not sent: provide chatId, phone, bsuid, or username | No recipient the channel could resolve. |
| 200 | wrong file | The media could not be fetched or uploaded — not a reachable URL, not valid base64. |
| 403 | access denied | The token is wrong, or belongs to a different channel than the URL. |
| 200 | Message was not sent: filename | sendFile called without a filename, so the media has no extension to send. |