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HTTP CompatibleAutomation Platform

Route SendiMessage events into Slack

Slack is where many teams want to see customer messaging activity — a reply arrived, a send failed, a line was blocked. There is no native SendiMessage Slack app today; what exists is plain HTTP compatibility, and it covers the useful direction well.

Point your SendiMessage webhook endpoint at a small handler (your backend, or a Zapier/Make/n8n flow), verify the X-SMSBridge-Signature header, and forward the events you care about to a Slack Incoming Webhook URL — receive events as 'new customer reply' notifications with a link to the conversation, outbound ERROR events as alerts. For the reverse direction, a Slack slash command or workflow can call your backend, which sends through POST /send-message; keep API credentials in your backend, never in Slack workflow configuration.

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What this integration enables

CRM triggers without code
Bridge CRM record changes to messaging with a Slack scenario instead of middleware.
Form and lead follow-up
New form submissions get a confirmation or next-step message.
E-commerce notifications
Order events from your store platform become customer updates.
Reply routing
SendiMessage webhooks trigger Slack flows that write replies into your CRM or helpdesk.

Implementation options

Slack Incoming Webhooks (via your handler or an automation platform)
Configure the request: POST https://api.sendimessage.com/v1/send-message, X-API-Key and X-API-Secret headers from the platform's credential store, and a JSON body mapped from trigger data.
Webhook trigger for events
Give SendiMessage a Slack webhook URL as your event endpoint, and delivery/reply events start flows that update your other systems.

Architecture

How it fits together: Slack event, then Workflow or backend, then SendiMessage API, then Managed messaging line, then SMS or supported iMessage, then Customer, then Delivery or reply event, then Signed webhook, then Slack timeline update.
  1. Slack eventA record changes, a stage moves, or a workflow fires
  2. Workflow or backendSlack automation or your middleware prepares the request
  3. SendiMessage APIPOST /send-message — the message is validated and queued
  4. Managed messaging lineYour dedicated line sends the message
  5. SMS or supported iMessageChannel routing picks iMessage where supported, SMS otherwise
  6. CustomerThe message arrives; the customer can reply
  7. Delivery or reply eventSendiMessage records what actually happened
  8. Signed webhookYour endpoint receives outbound or receive
  9. Slack timeline updateYour handler writes the event back as activity

Example request

HTTP action body
{
  "number": "{{trigger.phone}}",
  "content": "Hi {{trigger.first_name}}, your appointment is tomorrow at 10:00 AM.",
  "status_callback": "https://your-endpoint.example.com/status?record_id={{trigger.id}}"
}

Map the {{…}} placeholders from your Slack trigger data — the syntax shown is illustrative. status_callback is optional: it receives this message's delivery events, and because you compose the URL you can embed your own record id for correlation. Store the returned message_handle for the same purpose.

Delivery events and incoming replies

Use a Slack webhook trigger as your SendiMessage event endpoint: delivery confirmations and incoming replies then start flows that update the CRM, notify a channel, or open a ticket.

webhook event
// "outbound" event → your slack endpoint
// Verify the X-SMSBridge-Signature header (HMAC-SHA256 of the raw body
// with your webhook secret), then use GET /v2/messages/{message_handle}
// for authoritative state and match it to your record_id in slack.

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.
  • A published SendiMessage app in the Slack directory is not available today — the integration uses Slack Incoming Webhooks (via your handler or an automation platform), which is fully supported.

Security considerations

  • Store the API key in Slack's credential/connection store, not in plain text fields inside scenarios.
  • Restrict who can edit flows that send customer messages.
  • Keep phone numbers and message content out of run logs where the platform allows it.

Frequently asked questions

Is there a SendiMessage app in the Slack directory?
Not yet — statuses on this site only claim a published app when one has actually shipped. Slack Incoming Webhooks (via your handler or an automation platform) works today with the configuration on this page, and it exposes the full API.
What does a successful send look like?
The API responds with status "QUEUED" plus a message_handle you can store for correlation. Treat non-2xx responses as failures in your flow's error path.
Can flows react to delivery and replies?
Yes — register a Slack webhook URL as your SendiMessage event endpoint, and outbound / receive events become flow triggers.
Is there a native SendiMessage app for Slack?
No. Slack connects through webhooks and HTTP: SendiMessage events reach Slack through your handler or an automation platform, and Slack-initiated sends go through your backend. Statuses on this site only say an app exists when it has actually shipped.
Can my team answer customers from Slack?
Not directly today. Slack notifications link the team to the conversation, and replies are sent from the SendiMessage dashboard/team inbox or through your own integration calling the API.

Ready to connect Slack?

Request a messaging line and a SendiMessage integration specialist will review your Slack workflow and guide the setup.