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Re-engage a cold lead via WhatsApp API template

The scenario sends a personalised WhatsApp template to a lead or customer who showed interest earlier but went inactive.

Use case overview

The scenario sends a personalised WhatsApp template to a lead or customer who showed interest earlier but went inactive. The message includes their name, the product or topic they cared about, and an updated re-engagement hook. A static URL button opens the current offer or catalog page.

Template example

Hello, {{1}}! You previously showed interest in "{{2}}". {{3}} We would be happy to help again — open the current offer using the button below.

Open proposal
  • {{1}}
    customer or lead name
  • {{2}}
    product or service they previously showed interest in
  • {{3}}
    re-engagement hook (e.g. updated pricing, new feature, limited-time offer)
  • “Open proposal”
    button — fixed in the Meta template
WhatsApp Business API for re-engage previously interested lead

When to use it

Use this scenario when a contact opted in, showed real interest in a specific product or plan, and then went quiet — and something has since changed that is worth telling them about. It fits win-back campaigns, e-commerce carts left behind after a price change, and agencies running re-engagement for several client brands.

More revenue from contacts you already paid for
The campaign runs against contacts you already paid to acquire, so a reply costs a template send rather than a new click.
Fewer ignored, generic broadcasts
Three body variables carry the contact's name, the product they looked at and the reason to come back, so the message reads as a continuation, not a broadcast.
Less manual follow-up work
CRM flags the dormant segment and the template goes out on that event, so no rep rebuilds the list or retypes the offer for each contact.
Faster replies than email
The message arrives in WhatsApp, where an approved template can reach a contact outside the 24-hour window instead of waiting in an ignored mailbox.
Better win-back reporting
Delivery and read events return by webhook and are written back to the CRM, so the campaign reports on the same record it started from.

Workflow

  1. Trigger

    CRM or marketing automation flags a dormant contact with prior interest.

    event · triggered

  2. Capture event

    The system resolves the phone number and historical interest fields.

    phone: "+…"

  3. Build & send

    A personalised win-back template is built with three body variables and a static URL button.

    POST /sendTemplate

  4. Delivered

    The contact receives the WhatsApp re-engagement message.

    delivered

  5. Status tracked

    Delivery result is logged in CRM for the win-back campaign.

    status: "read"

WhatsApp Business API for re-engage previously interested lead

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_NEXTSTEP="___"         # {{3}} next step

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_NEXTSTEP=$TEST_NEXTSTEP"; do
    val="${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}} next step → ${TEST_NEXTSTEP}
read -r -d '' PAYLOAD <<JSON || true
{
  "phone": "${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_NEXTSTEP}" }
      ]
    }

  ]
}
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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