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Send WhatsApp promotions via API (offer template)

The scenario sends a personalised WhatsApp marketing template to opted-in contacts when a promotional campaign starts.

Use case overview

The scenario sends a personalised WhatsApp marketing template to opted-in contacts when a promotional campaign starts. The message includes the customer name, the promoted product or category, offer details, and the promotion end date. A static URL button opens the offer landing page.

Template example

Hello {{1}}! We have a special offer on {{2}}: {{3}}. The promotion is valid until {{4}}. Tap the button below to view the offer and shop now.

View offer
  • {{1}}
    customer name
  • {{2}}
    promoted product or category name
  • {{3}}
    promotional offer details (discount amount, conditions)
  • {{4}}
    offer valid until date
  • “View offer”
    button — fixed in the Meta template
WhatsApp Business API for promotional offer broadcast

When to use it

Use this scenario when you already have an opt-in WhatsApp marketing list and want to announce a discount or special offer to that base — not to cold contacts. It fits retail and e-commerce seasonal sales, SaaS upgrade promotions for existing subscribers, and agencies running promotional broadcasts for client brands from CRM segments.

Reach opted-in contacts outside the 24-hour window
An approved MARKETING template delivers the promotional offer on WhatsApp even when no conversation is open, so the campaign does not depend on a recent inbound message.
Offers that name the customer and the deal
Four body variables carry the contact name, promoted product or category, offer details, and expiry date, so the broadcast reads as a targeted promotion rather than a generic blast.
One tap to the promotion page
A static URL button fixed in the Meta template opens the offer landing page, so the contact can act on the discount without waiting inside the reply window.
Less manual campaign assembly
CRM or marketing automation supplies the segment and personalisation fields, and the template goes out on that trigger — no rep rebuilds the list or retypes offer terms for each contact.
Campaign delivery tracking
Delivery results are logged for campaign performance tracking, so marketing knows how many opted-in contacts received the offer before measuring conversions elsewhere.

Workflow

  1. Trigger

    Marketing or CRM selects an opted-in segment for the promotional campaign.

    event · triggered

  2. Capture event

    The system resolves phone numbers and promotion personalisation fields for each contact.

    phone: "+…"

  3. Build & send

    A personalised promotional template is built with four body variables and a static URL button.

    POST /sendTemplate

  4. Delivered

    Each opted-in contact receives the WhatsApp marketing offer message.

    delivered

  5. Status tracked

    Delivery results are logged for campaign performance tracking and follow-up.

    status: "read"

WhatsApp Business API for promotional offer broadcast

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_PRODUCTORSERVICENAME="___"         # {{2}} product or service name
TEST_DETAILS="___"         # {{3}} change details
TEST_DATE="___"         # {{4}} date or time

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=$TEST_CUSTOMERNAME" \
            "TEST_PRODUCTORSERVICENAME=$TEST_PRODUCTORSERVICENAME" \
            "TEST_DETAILS=$TEST_DETAILS" \
            "TEST_DATE=$TEST_DATE"; 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}} product or service name → ${TEST_PRODUCTORSERVICENAME}
# {{3}} change details → ${TEST_DETAILS}
# {{4}} date or time → ${TEST_DATE}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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": "${TEST_PRODUCTORSERVICENAME}" },
        { "type": "text", "text": "${TEST_DETAILS}" },
        { "type": "text", "text": "${TEST_DATE}" }
      ]
    }

  ]
}
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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