FreJun Teler Voice / Calls API

openapi: 3.2.0
info:
  title: Teler API Reference Voice / Calls API
  summary: Programmable voice infrastructure for AI agents.
  description: 'The Teler API lets you place and control programmable voice calls, stream live

    audio to AI agents, and observe everything that happens on a call in real time.'
  contact:
    name: Teler support
    email: support@frejun.com
  version: 0.1.0
servers:
- url: https://api.frejun.ai
  description: Production
security:
- ApiKeyAuth: []
tags:
- name: Voice / Calls
  description: Place outbound calls and read call state. A **call** (`cs_`) is the top-level session; each party on it is a **leg** (`cl_`).
paths:
  /api/v1/voice/calls/initiate:
    post:
      tags:
      - Voice / Calls
      summary: Initiate a call
      description: 'Place an outbound call. Teler dials `to_number` from `from_number`, and once the call connects it fetches your `flow_url` to drive the conversation. Status updates are delivered to `status_callback_url` for the lifetime of the call.


        The call is accepted asynchronously: a `202` means Teler has queued the call, not that the callee has answered. Track progress via webhooks or by polling **Retrieve a call**.'
      operationId: initiate_call
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CallInitiateRequest'
      responses:
        '202':
          description: The call was accepted and is being placed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CallInitiateResponse'
        '400':
          description: The call was rejected before dialing. The `code` and `message` are propagated from the call-control service and describe the specific reason; the values shown here are illustrative.
          content:
            application/json:
              example:
                success: false
                message: The from_number is not provisioned for outbound calls.
                code: from_number_not_provisioned
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: The `x-api-key` header is missing or invalid.
          content:
            application/json:
              example:
                success: false
                message: Invalid API Key.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: The request body or query parameters failed validation.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidationErrorResponse'
        '502':
          description: Teler could not reach the call-control service.
          content:
            application/json:
              example:
                success: false
                message: The call could not be initiated. Please try again.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '504':
          description: The call could not be initiated in time.
          content:
            application/json:
              example:
                success: false
                message: The call could not be initiated in time. Please try again.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
  /api/v1/voice/calls:
    get:
      tags:
      - Voice / Calls
      summary: List calls
      description: List your account's calls, newest first. Filter by state, numbers, or creation time, and page through results with cursors (see the Pagination section in the overview).
      operationId: list_voice_calls
      parameters:
      - name: state
        in: query
        required: false
        schema:
          anyOf:
          - $ref: '#/components/schemas/CallSessionState'
          - type: 'null'
          title: State
      - name: from_number
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          title: From Number
      - name: to_number
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          title: To Number
      - name: created_after
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Created After
      - name: created_before
        in: query
        required: false
        schema:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Created Before
      - name: limit
        in: query
        required: false
        schema:
          type: integer
          maximum: 100
          minimum: 1
          default: 50
          title: Limit
      - name: cursor_after
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Opaque cursor — page toward older rows (next page).
          title: Cursor After
        description: Opaque cursor — page toward older rows (next page).
      - name: cursor_before
        in: query
        required: false
        schema:
          anyOf:
          - type: string
          - type: 'null'
          description: Opaque cursor — page toward newer rows (previous page).
          title: Cursor Before
        description: Opaque cursor — page toward newer rows (previous page).
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CursorPage_CallSessionResponse_'
        '400':
          description: The pagination cursor is invalid or has expired.
          content:
            application/json:
              example:
                success: false
                message: The pagination cursor is invalid or has expired.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: The `x-api-key` header is missing or invalid.
          content:
            application/json:
              example:
                success: false
                message: Invalid API Key.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: The request body or query parameters failed validation.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidationErrorResponse'
  /api/v1/voice/calls/{call_id}:
    get:
      tags:
      - Voice / Calls
      summary: Retrieve a call
      description: Retrieve a single call by its identifier, including its legs.
      operationId: retrieve_voice_call
      parameters:
      - name: call_id
        in: path
        required: true
        schema:
          type: string
          title: Call Id
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CallSessionResponse'
        '403':
          description: The `x-api-key` header is missing or invalid.
          content:
            application/json:
              example:
                success: false
                message: Invalid API Key.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '404':
          description: No call matches the supplied identifier for this account.
          content:
            application/json:
              example:
                success: false
                message: The requested call was not found.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidationErrorResponse'
  /api/v1/voice/calls/{call_id}/legs:
    get:
      tags:
      - Voice / Calls
      summary: List call legs
      description: List the individual legs that make up a call, in creation order.
      operationId: list_call_legs
      parameters:
      - name: call_id
        in: path
        required: true
        schema:
          type: string
          title: Call Id
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CursorPage_CallLegResponse_'
        '403':
          description: The `x-api-key` header is missing or invalid.
          content:
            application/json:
              example:
                success: false
                message: Invalid API Key.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '404':
          description: No call matches the supplied identifier for this account.
          content:
            application/json:
              example:
                success: false
                message: The requested call was not found.
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidationErrorResponse'
components:
  schemas:
    CallSessionResponse:
      properties:
        id:
          type: string
          title: Id
          description: Unique identifier for the call (`cs_` prefix).
        account_id:
          type: string
          title: Account Id
          description: The account that owns the call (`acc_` prefix).
        voice_app_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Voice App Id
          description: The voice app that handled the call (`va_` prefix), if any.
        state:
          $ref: '#/components/schemas/CallSessionState'
          description: Current lifecycle state of the call.
        direction:
          $ref: '#/components/schemas/CallDirection'
          description: Whether the call was placed outbound or received inbound.
        from_number:
          anyOf:
          - type: string
          - type: 'null'
          title: From Number
          description: Caller number in E.164 format.
        to_number:
          anyOf:
          - type: string
          - type: 'null'
          title: To Number
          description: Called number in E.164 format.
        properties:
          additionalProperties: true
          type: object
          title: Properties
          description: Arbitrary metadata you attached when initiating the call.
        created_at:
          type: string
          format: date-time
          title: Created At
          description: When the call was created.
        answered_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Answered At
          description: When the call was answered, if it was.
        ended_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Ended At
          description: When the call ended, if it has.
        reason:
          anyOf:
          - type: string
          - type: 'null'
          title: Reason
          description: Machine-readable reason the call ended.
        legs:
          items:
            $ref: '#/components/schemas/CallLegResponse'
          type: array
          title: Legs
          description: The individual legs that make up this call.
      type: object
      required:
      - id
      - account_id
      - state
      - direction
      - created_at
      title: CallSessionResponse
      example:
        account_id: acc_01JQ8Z9K7M3N2P4R5S6T7V8WIJ
        answered_at: '2026-06-01T09:15:12Z'
        created_at: '2026-06-01T09:15:04Z'
        direction: outbound
        from_number: '+14155552671'
        id: cs_01JQ8Z9K7M3N2P4R5S6T7V8W9X
        legs: []
        properties: {}
        state: answered
        to_number: '+14155559876'
        voice_app_id: va_01JQ8Z9K7M3N2P4R5S6T7V8WKL
    CallLegRole:
      type: string
      enum:
      - primary
      - dial_target
      - transfer_target
      - monitor
      - parked
      title: CallLegRole
    CallInitiateRequest:
      properties:
        from_number:
          type: string
          maxLength: 16
          minLength: 8
          pattern: ^\+\d{7,15}$
          title: From Number
          description: The number to place the call from, in E.164 format. Must be a number you own.
        to_number:
          type: string
          maxLength: 16
          minLength: 8
          pattern: ^\+\d{7,15}$
          title: To Number
          description: The destination number to dial, in E.164 format.
        flow_url:
          type: string
          maxLength: 2083
          minLength: 1
          format: uri
          title: Flow Url
          description: HTTPS URL Teler fetches when the call connects to obtain the call flow that drives the call.
        status_callback_url:
          type: string
          maxLength: 2083
          minLength: 1
          format: uri
          title: Status Callback Url
          description: HTTPS URL that receives status webhooks for the lifetime of the call.
        record:
          type: boolean
          title: Record
          description: Whether to record the call. Defaults to `true`.
          default: true
      type: object
      required:
      - from_number
      - to_number
      - flow_url
      - status_callback_url
      title: CallInitiateRequest
      example:
        flow_url: https://example.com/flows/123
        from_number: '+14155552671'
        record: true
        status_callback_url: https://yourapp.com/callback
        to_number: '+14155559876'
    ValidationErrorResponse:
      properties:
        success:
          type: boolean
          title: Success
          description: Always `false`.
          default: false
        message:
          type: string
          title: Message
          description: Always `"Validation Error"` for this response.
          default: Validation Error
        errors:
          items:
            $ref: '#/components/schemas/ValidationFieldError'
          type: array
          title: Errors
          description: One entry per field that failed validation.
      type: object
      required:
      - errors
      title: ValidationErrorResponse
      description: Returned with `422` when the request fails schema validation.
      example:
        errors:
        - loc:
          - body
          - to_number
          msg: String should match pattern '^\+\d{7,15}$'
          type: string_pattern_mismatch
        message: Validation Error
        success: false
    ValidationFieldError:
      properties:
        loc:
          items: {}
          type: array
          title: Loc
          description: Path to the offending field, e.g. `["body", "to_number"]`.
        msg:
          type: string
          title: Msg
          description: Human-readable explanation of the problem.
        type:
          type: string
          title: Type
          description: Programmatic error type, e.g. `string_pattern_mismatch`.
      type: object
      required:
      - loc
      - msg
      - type
      title: ValidationFieldError
      description: One field-level problem within a `422` validation error.
    CallLegState:
      type: string
      enum:
      - created
      - ringing
      - answered
      - completed
      - failed
      title: CallLegState
    CursorPage_CallSessionResponse_:
      properties:
        data:
          items:
            $ref: '#/components/schemas/CallSessionResponse'
          type: array
          title: Data
          description: The page of results, newest first.
        next_cursor:
          anyOf:
          - type: string
          - type: 'null'
          title: Next Cursor
          description: Pass as `cursor_after` to fetch the next (older) page. `null` on the last page.
        previous_cursor:
          anyOf:
          - type: string
          - type: 'null'
          title: Previous Cursor
          description: Pass as `cursor_before` to fetch the previous (newer) page. `null` on the first page.
        has_more:
          type: boolean
          title: Has More
          description: Whether more results exist after this page.
          default: false
      type: object
      required:
      - data
      title: CursorPage[CallSessionResponse]
    CallSessionState:
      type: string
      enum:
      - initiated
      - ringing
      - answered
      - completed
      - failed
      title: CallSessionState
    ErrorResponse:
      properties:
        success:
          type: boolean
          title: Success
          description: Always `false` on an error response.
          default: false
        message:
          type: string
          title: Message
          description: Human-readable description of what went wrong. Safe to show to a user.
        code:
          anyOf:
          - type: string
          - type: 'null'
          title: Code
          description: Stable, machine-readable error code. Present on business-rule errors (e.g. `transfer_in_progress`). Branch on this, not on `message`.
        type:
          anyOf:
          - type: string
          - type: 'null'
          title: Type
          description: Error category (e.g. `invalid_state`). Present on some conflict errors.
      type: object
      required:
      - message
      title: ErrorResponse
      description: Standard error envelope returned for all non-validation errors.
      example:
        message: The requested call was not found.
        success: false
    CursorPage_CallLegResponse_:
      properties:
        data:
          items:
            $ref: '#/components/schemas/CallLegResponse'
          type: array
          title: Data
          description: The page of results, newest first.
        next_cursor:
          anyOf:
          - type: string
          - type: 'null'
          title: Next Cursor
          description: Pass as `cursor_after` to fetch the next (older) page. `null` on the last page.
        previous_cursor:
          anyOf:
          - type: string
          - type: 'null'
          title: Previous Cursor
          description: Pass as `cursor_before` to fetch the previous (newer) page. `null` on the first page.
        has_more:
          type: boolean
          title: Has More
          description: Whether more results exist after this page.
          default: false
      type: object
      required:
      - data
      title: CursorPage[CallLegResponse]
    CallInitiateData:
      properties:
        id:
          type: string
          title: Id
          description: Identifier of the newly created call (`cs_` prefix).
        from_number:
          type: string
          title: From Number
          description: The number the call is placed from.
        to_number:
          type: string
          title: To Number
          description: The number being dialed.
        status_callback_url:
          type: string
          maxLength: 2083
          minLength: 1
          format: uri
          title: Status Callback Url
          description: Where status webhooks will be delivered.
        record:
          type: boolean
          title: Record
          description: Whether the call is being recorded.
      type: object
      required:
      - id
      - from_number
      - to_number
      - status_callback_url
      - record
      title: CallInitiateData
    CallLegResponse:
      properties:
        id:
          type: string
          title: Id
          description: Unique identifier for this leg (`cl_` prefix).
        call_session_id:
          type: string
          title: Call Session Id
          description: The call this leg belongs to (`cs_` prefix).
        direction:
          $ref: '#/components/schemas/CallDirection'
          description: Whether the leg dialed out or was received.
        role:
          $ref: '#/components/schemas/CallLegRole'
          description: The leg's role within the call.
        state:
          $ref: '#/components/schemas/CallLegState'
          description: Current lifecycle state of the leg.
        from_number:
          anyOf:
          - type: string
          - type: 'null'
          title: From Number
          description: Caller number in E.164 format.
        to_number:
          anyOf:
          - type: string
          - type: 'null'
          title: To Number
          description: Called number in E.164 format.
        parent_leg_id:
          anyOf:
          - type: string
          - type: 'null'
          title: Parent Leg Id
          description: The leg that spawned this one (e.g. for transfers), if any.
        recordings:
          items:
            type: string
          type: array
          title: Recordings
          description: Recording identifiers (`rec_` prefix) captured on this leg.
        created_at:
          type: string
          format: date-time
          title: Created At
          description: When the leg was created.
        answered_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Answered At
          description: When the leg was answered, if it was.
        ended_at:
          anyOf:
          - type: string
            format: date-time
          - type: 'null'
          title: Ended At
          description: When the leg ended, if it has.
        reason:
          anyOf:
          - type: string
          - type: 'null'
          title: Reason
          description: Machine-readable reason the leg ended.
        ended_by:
          anyOf:
          - type: string
          - type: 'null'
          title: Ended By
          description: Which party ended the leg.
      type: object
      required:
      - id
      - call_session_id
      - direction
      - role
      - state
      - created_at
      title: CallLegResponse
      example:
        answered_at: '2026-06-01T09:15:12Z'
        call_session_id: cs_01JQ8Z9K7M3N2P4R5S6T7V8W9X
        created_at: '2026-06-01T09:15:04Z'
        direction: outbound
        from_number: '+14155552671'
        id: cl_01JQ8Z9K7M3N2P4R5S6T7V8WAB
        recordings:
        - rec_01JQ8Z9K7M3N2P4R5S6T7V8WEF
        role: primary
        state: answered
        to_number: '+14155559876'
    CallDirection:
      type: string
      enum:
      - inbound
      - outbound
      title: CallDirection
    CallInitiateResponse:
      properties:
        message:
          type: string
          title: Message
          description: Human-readable confirmation message.
        data:
          $ref: '#/components/schemas/CallInitiateData'
          description: Details of the accepted call.
      type: object
      required:
      - message
      - data
      title: CallInitiateResponse
      example:
        data:
          from_number: '+14155552671'
          id: cs_01JQ8Z9K7M3N2P4R5S6T7V8W9X
          record: true
          status_callback_url: https://yourapp.com/callback
          to_number: '+14155559876'
        message: Call initiated successfully
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: Your secret account API key. Create one in the Teler dashboard.