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E-signature request via WhatsApp API template

The scenario sends the client a personalised WhatsApp template when they must sign a document or confirm submitted data to continue.

Use case overview

The scenario sends the client a personalised WhatsApp template when they must sign a document or confirm submitted data to continue. The message includes the client name, the document or process label, and signing instructions. A static URL button opens the signature or data-confirmation portal.

Template example

Hello, {{1}}! Please review and sign your {{2}}. {{3}} Tap the button below to sign or confirm your data. If you have questions — we are here to help.

Sign document
  • {{1}}
    customer name
  • {{2}}
    document or process to sign (e.g. service agreement, loan application, data confirmation)
  • {{3}}
    signing or confirmation instructions (e.g. review terms and sign electronically in the portal by Friday)
  • “Sign document”
    button — fixed in the Meta template
WhatsApp Business API for signature or data confirmation request

When to use it

Reach for this scenario when a client must sign a document or confirm submitted data before onboarding, compliance, or a service request can proceed — and they have not completed the step yet, with no open WhatsApp conversation to reach them in session. It fits product teams waiting on contract signatures, fintech flows that need application data confirmed before approval, and agencies wiring CRM, BPM, or e-sign provider gates into WhatsApp signature nudges.

Signatures collected without email chase
Three body variables carry the client name, document or process label, and signing instructions, so the request explains exactly what to sign or confirm instead of a generic "complete your profile" blast.
Signing portal one tap away
A static URL button labeled Sign document opens the e-sign or data-confirmation portal — the link is fixed in the approved Meta template while only the body text is sent via the API.
Reach clients outside the 24-hour window
Because there is no active conversation, the send uses an approved WhatsApp template via the 1MSG API — the only channel that can prompt a signature when the client has not written first.
No manual follow-up for every pending signature
When a signature-or-confirmation-required trigger fires from onboarding, compliance, or support, the system resolves the phone number and sends the template on that event instead of someone copying signing instructions by hand.
Delivery logged for workflow follow-up
Delivery result is logged after send, so CRM or compliance teams can see who was asked to sign and handle errors according to platform rules.

Workflow

  1. Customer acts

    A business rule or workflow requires the client to sign a document or confirm submitted data.

    user action

  2. Capture event

    The system detects the signature-or-confirmation-required event and resolves the recipient phone number.

    phone: "+…"

  3. Build & send

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

    POST /sendTemplate

  4. Delivered

    The client receives the WhatsApp signature or data-confirmation request with process context and instructions.

    delivered

  5. Status tracked

    Delivery result is logged; the client can sign or confirm via the portal link.

    status: "read"

WhatsApp Business API for signature or data confirmation request

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_PROCESS="___"         # {{2}} process 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=$TEST_CUSTOMERNAME" \
            "TEST_PROCESS=$TEST_PROCESS" \
            "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}} process name → ${TEST_PROCESS}
# {{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": "${TEST_PROCESS}" },
        { "type": "text", "text": "${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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