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Event invitation via WhatsApp API template

The scenario sends a personalised WhatsApp marketing template to opted-in contacts when an upcoming public event is announced.

Use case overview

The scenario sends a personalised WhatsApp marketing template to opted-in contacts when an upcoming public event is announced. The message includes the contact name, the event name, and the scheduled date and time. A static URL button opens the registration page.

Template example

Hello {{1}}! You are invited to {{2}} on {{3}}. Tap the button below to register and save your spot.

Register
  • {{1}}
    customer or contact name
  • {{2}}
    event name (webinar, workshop, meetup, or open day)
  • {{3}}
    event date and time
  • “Register”
    button — fixed in the Meta template
WhatsApp Business API for event invitation broadcast

When to use it

Use this scenario when you already have an opt-in WhatsApp marketing list and want to invite those contacts to a public event — a webinar, workshop, offline meetup, or open day — with a clear date and a registration link. It is not for reminding someone about a personal booking they already made; it fits education and SaaS product demos, retail store events, and agencies promoting client events from CRM segments.

Fill events from contacts who already opted in
An approved MARKETING template reaches opted-in contacts outside the 24-hour window, so invitations go out on WhatsApp instead of relying on email open rates alone.
Invitations that name the person and the event
Three body variables carry the contact name, event title, and scheduled date and time, so the message reads as a personal invite rather than a generic blast.
One tap to the registration page
A static URL button fixed in the Meta template opens the event registration page, so the contact can sign up without waiting inside the reply window.
Less manual invite assembly
CRM or marketing automation supplies the segment and event fields, and the template goes out on that trigger — no rep rebuilds the list or retypes event details for each contact.
Invitation delivery tracking
Delivery results are logged for the event campaign, so marketing knows how many opted-in contacts received the invite before measuring registrations elsewhere.

Workflow

  1. Trigger

    Marketing or CRM selects an opt-in segment for the upcoming event.

    event · triggered

  2. Capture event

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

    phone: "+…"

  3. Build & send

    A personalised invitation template is built with three body variables and a static URL button.

    POST /sendTemplate

  4. Delivered

    Each invited contact receives the event invitation on WhatsApp.

    delivered

  5. Status tracked

    Delivery results are logged for event registration campaign tracking.

    status: "read"

WhatsApp Business API for event invitation 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_TOPIC="___"         # {{2}} topic or subject
TEST_DATE="___"         # {{3}} 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=$TEST_CUSTOMERNAME" \
            "TEST_TOPIC=$TEST_TOPIC" \
            "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}} topic or subject → ${TEST_TOPIC}
# {{3}} 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": "${TEST_TOPIC}" },
        { "type": "text", "text": "${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

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