API Integration GuideWorkflow + HTTP Request

Integrate delivery notifications with your dispatch system

Failed deliveries are usually information failures — the customer didn't know the window, or the driver couldn't reach them. Delivery-notification integration closes that gap from the systems that already know the truth: your dispatch, fleet, or logistics platform.

Dispatch events (driver assigned, en route, 15 minutes out) post to the SendiMessage API with the delivery id embedded in the status_callback URL. Customers can reply with access instructions, and those replies return to dispatch through the webhook before the driver is standing at the wrong gate.

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What this integration enables

Window announcement

When the route is planned, customers learn their delivery window.

Driver en route

A '15 minutes away' message cuts failed first attempts.

Access instructions

Replies with gate codes or drop instructions reach dispatch in time to matter.

Failed attempt follow-up

A miss triggers an immediate reschedule message instead of a paper slip.

Proof of notification

Delivery events document that the customer was informed, per stop.

Architecture

Dispatch eventRoute planned, driver assigned, approaching stop
Your handlerBuilds the message from stop + ETA data
SendiMessage APIPOST /send-message with the delivery id in the status_callback URL
CustomerNotification arrives; replies flow back
Webhook eventsDelivery status and customer replies return to dispatch

Example request

cURL

curl -sS https://api.sendimessage.com/v1/send-message \
  -H "X-API-Key: $SENDIMESSAGE_API_KEY" \
  -H "X-API-Secret: $SENDIMESSAGE_API_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "number": "+15555550123",
    "content": "Your appointment is tomorrow at 10:00 AM."
  }'
# → {
#   "status": "QUEUED",
#   "message_handle": "4e828182-a640-483f-bfe9-17ffcaa51d48",
#   "to": "+14155550123",
#   "service": null,
#   "is_outbound": true,
#   "error_message": null,
#   "date_sent": null
# }

Delivery events and incoming replies

Match replies by the customer's number to the active stop, so access notes and timing constraints land on the right delivery in your dispatch board.

webhook event

// "outbound" event → your your_dispatch endpoint
// Verify the SendiMessage-Signature header (t={timestamp},v1=HMAC-SHA256 of
// "{timestamp}.{raw body}", keyed with your webhook secret), then use
// GET /v2/messages/{message_handle} for authoritative state and match it to
// your delivery_id in your_dispatch.

Limitations and honest notes

iMessage delivery is available on supported messaging lines and destinations. Recipients without iMessage receive SMS when fallback is configured — never assume universal iMessage availability.
Messages are accepted asynchronously — the API returns status QUEUED and final status arrives via webhook or the message endpoints.
No official SDK for this ecosystem yet — the example uses plain HTTP against the REST API. Official SDKs are published for JavaScript/TypeScript (npm: sendimessage), Python (PyPI: sendimessage), PHP (Composer: sendimessage/sdk), and Go (github.com/sendimessage/sendimessage-go). Every SDK is dependency-free and covers the full public API surface.
Send messages only to recipients who expect them. Transactional and operational messaging is the primary use case — unsolicited bulk marketing is not.

Frequently asked questions

Can drivers' apps trigger the messages?

Anything server-side can: when the driver app reports 'next stop', your backend fires the en-route message. Keep the API key on the server — the driver app calls your backend, not SendiMessage.

One line or many?

Typically one line per operating market keeps sender identity consistent. The team sizes this with you during onboarding.

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