> ## Documentation Index > Fetch the complete documentation index at: https://docs.orbit.devotel.io/llms.txt > Use this file to discover all available pages before exploring further. # Preview smart-send per-contact schedule > Computes a preview of the smart-send schedule for the campaign's resolved audience: for each contact, the optimal send time derived from that contact's own engagement profile, plus an hour-of-day distribution histogram so operators can confirm the timing before launching. When the campaign declares more than one channel, the response also includes a `next_best_channel` block ranking the channel most likely to engage each previewed contact. Read-only and advisory — it never enqueues a job or changes what the execution worker dispatches. The preview is bounded to a window of contacts for a fast response; no request body is required. ## OpenAPI ````yaml /openapi.yaml post /api/v1/campaigns/{id}/preview-smart-send openapi: 3.1.0 info: title: Devotel CPaaS API description: Orbit by Devotel — Communications Platform as a Service API version: 1.0.0 contact: name: Devotel url: https://devotel.io email: support@devotel.io license: name: Proprietary servers: - url: https://api.orbit.devotel.io description: Production security: - Bearer: [] - ApiKey: [] tags: - name: Messages description: >- Send and manage messages across all channels (SMS, WhatsApp, RCS, Email, Viber, etc.) - name: Fax description: >- List and track fax (MMS/T.38) transmissions on Telnyx-backed fax numbers (sending flows through the Messaging API) - name: Agents description: AI agent creation, configuration, and execution - name: Voice description: Voice calls, IVR, conferencing, and SIP trunking - name: OnCall description: On-call rotations and escalation policy planning for incident alerting - name: Webhooks description: Webhook endpoint management and delivery logs - name: Numbers description: Phone number search, provisioning, and configuration - name: Brand Identity description: >- Unified cross-channel brand trust posture (10DLC, toll-free, WhatsApp, RCS, branded calling, number KYC) - name: Contacts description: Contact management, segmentation, and lifecycle tracking - name: Campaigns description: Marketing campaign orchestration and analytics - name: Flows description: Automation flow builder and execution engine - name: Templates description: Message template management and approval workflows - name: Settings description: Organization, channel, and user preference settings - name: Verify description: OTP generation and verification across channels - name: Push description: Push notification delivery via FCM and APNs - name: Integrations description: Third-party service connections and OAuth management - name: CDP description: >- Customer Data Platform — activation surface (CRM object sync, streaming destinations, ad-audience activation) - name: Files description: >- Server-to-server media upload, listing, retrieval, and deletion (signed-URL backed) - name: Commerce description: >- Omnichannel conversational-commerce — persistent cart + checkout state machine, channel-agnostic hosted pay-by-link, native WhatsApp checkout, and AP2-style agent payment mandates. - name: Sync description: >- Real-time shared-state primitive (Twilio Sync parity) — Documents, Maps, Lists, and ephemeral Streams, with change events relayed over the /api/v1/ws/sync WebSocket gateway - name: Risk description: >- Unified cross-channel Trust & Fraud risk scoring — fuses SMS-pumping, URL-reputation, Verify Fraud Guard, and Voice Biometrics signals into one composite verdict queryable before a send or a call. - name: Orby description: >- In-dashboard Orby operator assistant: streamed assistant turns, conversation threads, product knowledge-base search, and the tool-action approval gate. Available to signed-in operators only (dashboard session auth — API-key requests are rejected). paths: /api/v1/campaigns/{id}/preview-smart-send: post: tags: - Campaigns summary: Preview smart-send per-contact schedule description: >- Computes a preview of the smart-send schedule for the campaign's resolved audience: for each contact, the optimal send time derived from that contact's own engagement profile, plus an hour-of-day distribution histogram so operators can confirm the timing before launching. When the campaign declares more than one channel, the response also includes a `next_best_channel` block ranking the channel most likely to engage each previewed contact. Read-only and advisory — it never enqueues a job or changes what the execution worker dispatches. The preview is bounded to a window of contacts for a fast response; no request body is required. parameters: - schema: type: string in: path name: id required: true requestBody: required: false content: application/json: schema: type: object description: >- No body fields are read; the audience is resolved from the campaign. Send an empty object. additionalProperties: false responses: '200': description: Per-contact smart-send schedule preview. content: application/json: schema: type: object properties: data: type: object properties: campaign_id: type: string total_audience: type: integer preview_count: type: integer description: Number of contacts in this bounded preview window. profile_count: type: integer description: Contacts scheduled from a real engagement profile. fallback_count: type: integer description: Contacts scheduled from the default fallback time. distribution_utc: type: array description: 24-bucket hour-of-day histogram of scheduled sends. items: type: object properties: hour: type: integer count: type: integer schedule: type: array items: type: object properties: contactId: type: string scheduledAt: type: string format: date-time next_best_channel: type: object description: >- Present only for multi-channel campaigns; per-contact recommended channel. properties: candidate_channels: type: array items: type: string profile_count: type: integer fallback_count: type: integer recommendations: type: array items: type: object properties: contact_id: type: string channel: type: string source: type: string enum: - profile - fallback meta: type: object properties: request_id: type: string timestamp: type: string format: date-time '404': description: Campaign not found. components: securitySchemes: Bearer: type: http scheme: bearer bearerFormat: JWT description: Dashboard JWT token from Clerk ApiKey: type: apiKey name: X-API-Key in: header description: Server-to-server API key (dv_live_sk_*) ````