> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tetherai.ca/llms.txt
> Use this file to discover all available pages before exploring further.

# Handle inbound SMS webhook (Sinch)

> Inbound webhook called by Sinch when an SMS is delivered to a Tether-provisioned number. Responds 200 immediately to prevent Sinch retries and processes the message asynchronously (contact upsert, conversation routing, automation triggering, AI reply pipeline).



## OpenAPI

````yaml /api-reference/openapi.yaml post /api/webhook
openapi: 3.0.3
info:
  title: Tether Relay and Tether API
  version: 1.0.0
  description: >-
    Route-derived OpenAPI contract generated from tether-relay backend sources.
    Regenerate with scripts/sync-openapi-from-backend.mjs.
servers:
  - url: https://your-instance.example.com
    description: Production
  - url: http://localhost:2212
    description: Local API service
security: []
tags:
  - name: AI
  - name: Applications
  - name: Approval
  - name: Auth
  - name: Automations
  - name: Calls
  - name: Campaigns
  - name: Contact Analytics
  - name: Contact Metrics
  - name: Contact Notes
  - name: Contacts
  - name: Conversation Monitor
  - name: Conversations
  - name: Departments
  - name: Email
  - name: Escalation Dashboard
  - name: Event Logs
  - name: Google Sheets
  - name: Marketplace
  - name: Messages
  - name: Notification Sounds
  - name: Notifications
  - name: Org Snapshots
  - name: Organizations
  - name: Outreach
  - name: Outreach Metrics
  - name: Outreach Sources
  - name: Pipelines
  - name: Processes
  - name: Prompts
  - name: Reminders
  - name: Sms
  - name: Templates
  - name: Traces
  - name: Training
  - name: Upload
  - name: User Snapshots
  - name: Users
  - name: Vertical
  - name: Webchats
  - name: Webhook
paths:
  /api/webhook:
    post:
      tags:
        - Webhooks
      summary: Handle inbound SMS webhook (Sinch)
      description: >-
        Inbound webhook called by Sinch when an SMS is delivered to a
        Tether-provisioned number. Responds 200 immediately to prevent Sinch
        retries and processes the message asynchronously (contact upsert,
        conversation routing, automation triggering, AI reply pipeline).
      operationId: post_webhook
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SmsWebhookRequest'
      responses:
        '200':
          description: Webhook accepted (immediate ack — processing continues async)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SmsWebhookAckResponse'
        '500':
          description: Webhook processing failed
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/WebhookErrorResponse'
components:
  schemas:
    SmsWebhookRequest:
      type: object
      properties:
        id:
          type: string
          description: >-
            Sinch-assigned inbound message id; echoed back in the ack for log
            correlation.
        from:
          type: string
          description: >-
            Sender phone number (Sinch may omit the `+`; the handler normalizes
            to E.164).
        to:
          type: string
          description: Tether-provisioned recipient number that received the SMS.
        body:
          type: string
          description: SMS text content as delivered by the carrier.
        operator_id:
          type: string
          description: Sinch carrier/operator identifier for the originating network.
        received_at:
          type: string
          description: ISO-8601 timestamp at which Sinch ingested the message.
        type:
          type: string
          description: Sinch event type, e.g. `mo_text` for an inbound text message.
      required:
        - id
        - from
        - to
        - body
      additionalProperties: true
      example:
        id: 01K608PQBF3H41EQS64AH7CE11
        from: '14165550100'
        to: '12362320246'
        body: Hey, can you call me back?
        operator_id: '310010'
        received_at: '2026-05-18T15:04:01.135Z'
        type: mo_text
    SmsWebhookAckResponse:
      type: object
      description: >-
        Immediate ack returned to Sinch for an inbound SMS. Tether persists +
        routes the message asynchronously.
      properties:
        message:
          type: string
        messageId:
          type: string
          description: >-
            Sinch message id from the inbound payload, echoed back for log
            correlation.
      required:
        - message
        - messageId
      additionalProperties: true
      example:
        message: Webhook received
        messageId: 01K608PQBF3H41EQS64AH7CE11
    WebhookErrorResponse:
      type: object
      description: >-
        Error envelope used across provider webhook routes. Most failures only
        carry `error`; a few (ElevenLabs tool errors, ingress validation) add
        `success:false`, `message`, or a `code`. Many of these endpoints respond
        200 with `success:false` for recoverable cases (especially the
        ElevenLabs server tools) — only hard failures use 4xx/5xx.
      properties:
        error:
          type: string
        message:
          type: string
        success:
          type: boolean
          enum:
            - false
        code:
          type: string
        details:
          description: Optional diagnostic detail (stack snippet, validation issues, etc.).
      additionalProperties: true
      example:
        error: Webhook processing failed

````