GSMA Unconditional Call Forwarding information retrieval API

openapi: 3.2.0
info:
  title: Call Forwarding Signal Unconditional Call Forwarding information retrieval API
  description: '# Overview

    The Call Forwarding Signal (CFS) API provides the API Consumer with

    information about the status of the Call Forwading Service on a specific

    phone number. The main scope of the CFS API is "anti Fraud" to avoid

    fraudsters to use the Call Forwarding Service to carry on a scam. Other use

    cases are anyway supported by the CFS API that also provides additional

    endpoints to detect the general Call Forwarding Service settings.

    # Introduction

    The Call Forwarding Service is provided by the Network to a phone

    number. This service redirects the incoming call to that phone number

    to an alternative destination such as another phone number or a voice mail

    system. There are two main types of call forwarding settings:

    unconditional and conditional.

    The CFS API can be invoked to detect if the unconditional

    call forwarding service is active. The CSF API can also be invoked to

    get the general status of the Call Forwarding Service (inactive,

    conditional, unconditional). If conditional call forwarding is active,

    the differente type of settings are returned (''conditional_busy'',

    ''conditional_unavailable'', ''conditional_no_reply'').\

    \

    **Example use cases:**\

    \

    [**Bank Frauds**](https://github.com/camaraproject/CallForwardingSignal\

    /discussions/3#discussioncomment-8694420)\

    \

    [**Alert Interception**](https://github.com/camaraproject/CallForwarding\

    Signal/discussions/3#discussioncomment-8701847)\

    \

    [**Call Forwading Verification**](https://github.com/camaraproject/\

    CallForwarding\Signal/discussions/3#discussioncomment-8915595)

    # Quick Start

    The CFS API is a REST API based on the CreateCallForwardingSignal resource.

    This resource can be filled during the API invokation, by the API Consumer,

    with the phone number on which the Call Forwarding Service status must be

    verified. Anyway the phone number is also detected, by the API Producer,

    from the access token.\

    \

    Before starting to use the Call Forwarding API, the developer needs to know

    about the below specified details:\

    \

    **phoneNumber**

    This is the end user phone number. The CFS API verifies if a call forwarding

    service is active on this phone number. Note: the value of this optional

    parameter must match the value of the phone number retrieved from the access

    token.\

    \

    **CreateCallForwardingSignal**

    This is the resource the API Consumer uses to define the phone number to

    be verified about the status of the Network Call Forwarding service.\

    \

    **UnconditionalCallForwardingSignal**

    This is the resource the API Consumer gets back, containing the information

    about the Unconditional Call Forwarding Service status for the given phone

    number (PhoneNumber)\

    \

    **CallForwardingSignal**

    This is the resource the API Consumer gets back, containing the information

    about the general status of the Network Call Forwarding service for the

    specified phone number.\

    \

    The CFS API provides two endpoints fulfilling the following intents:

    - **unconditional-call-forwardings**: Is the unconditional call fwd service

    active on a specific phone number?

    - **call-forwardings**: Which is the status of the call forwarding for a

    specific phone number?

    # Authorization and authentication

    The "Camara Security and Interoperability Profile" provides details on how

    a client requests an access token. Please refer to Identify and Consent

    Management (https://github.com/camaraproject/IdentityAndConsentManagement/)

    for the released version of the Profile.\

    \

    Which specific authorization flows are to be used will be determined during

    onboarding process, happening between the API Client and the Telco Operator

    exposing the API, taking into account the declared purpose for accessing the

    API, while also being subject to the prevailing legal framework dictated by

    local legislation.\

    \

    It is important to remark that in cases where personal user data is

    processed by the API, and users can exercise their rights through mechanisms

    such as opt-in and/or opt-out, the use of 3-legged access tokens becomes

    mandatory. This measure ensures that the API remains in strict compliance

    with user privacy preferences and regulatory obligations, upholding the

    principles of transparency and user-centric data control.

    # Identifying the phone number from the access token

    This specification defines the "phoneNumber" field as optional in API

    requests because using a 3-legged access token the phone number can be

    uniquely identified by the token.

    ## Handling of phone number information:

    ### Optional phone number object for 3-legged tokens:

    When using a 3-legged access token, the phone number associated with the

    access token must be considered as the phone number for the API request.

    This means that the "phoneNumber" paramenter is not required in the request,

    and if it is included it must identify the same phone number.

    ### Validation mechanism:

    - The server will extract the phone number identification from the access

    token, if available.

    - If the API request additionally includes a "phoneNumber" parameter when

    using a 3-legged access token, the API will validate that the phone number

    identifier provided matches the one associated with the access token.

    - If there is a mismatch, the API will respond with a

    403 `INVALID_TOKEN_CONTEXT` error, indicating that the device information

    in the request does not match the token.

    ### Error handling for unidentifiable devices:

    - If the "phoneNumber" parameter is not included in the request and the

    phone number information cannot be derived from the 3-legged access token,

    the server will return a 422 `UNIDENTIFIABLE_DEVICE` error.

    # API Documentation

    ## Details

    The CFS API is invoked by an API Consumer after the Consent Management

    flow.\

    The API Consumer can request the API Producer for the status of the

    Unconditional Call Forwarding service using the

    unconditional-call-forwardings POST method. A boolean, with the information

    about the activation status of the call forwarding service, will be

    provided back via the UnconditionalCallForwardingSignal resource.\

    The API Consumer can also request the API Producer for the generic status of

    the Call Forwarding service using the call-forwardings POST method. An array

    of strings with the information of the type of active call forwarding

    services will be provided back via the CallForwardingSignal resource.\

    CFS API have to check the Call Forwarding

    Service status can be optionally defined with resource

    (CreateCallForwardingSignal) containing the phone number (PhoneNumber)

    to be checked.

    # FAQ''s

    (FAQs will be added in a later version of the documentation)

    '
  version: 0.2.0
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0.html
  x-camara-commonalities: 0.4.0
servers:
- url: '{apiRoot}/call-forwarding-signal/v0.2'
  variables:
    apiRoot:
      default: http://localhost:9091
      description: API root, defined by the service provider, e.g. `api.example.com` or `api.example.com/somepath`
tags:
- name: Unconditional Call Forwarding information retrieval
  description: Provides information on Unconditional Call Forwarding settings for the provided phone number (PhoneNumber)
paths:
  /unconditional-call-forwardings:
    post:
      tags:
      - Unconditional Call Forwarding information retrieval
      security:
      - openId:
        - call-forwarding-signal:unconditional-call-forwardings:read
      summary: Retrieve the information about the status of the unconditional call forwarding service on a phone number (PhoneNumber)
      description: This endpoint provides information about the status of the unconditional call forwarding, beeing active or not.
      operationId: retrieveUnconditionalCallForwarding
      parameters:
      - $ref: '#/components/parameters/x-correlator'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateCallForwardingSignal'
        required: true
      responses:
        '200':
          description: OK.
          headers:
            x-correlator:
              $ref: '#/components/headers/x-correlator'
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/UnconditionalCallForwardingSignal'
        '400':
          $ref: '#/components/responses/Generic400'
        '404':
          $ref: '#/components/responses/Generic404'
        '500':
          $ref: '#/components/responses/Generic500'
        '504':
          $ref: '#/components/responses/Generic504'
        '401':
          $ref: '#/components/responses/Generic401'
        '403':
          $ref: '#/components/responses/Generic403'
        '409':
          $ref: '#/components/responses/Generic409'
        '415':
          $ref: '#/components/responses/Generic415'
        '422':
          $ref: '#/components/responses/Generic422'
        '429':
          $ref: '#/components/responses/Generic429'
        '503':
          $ref: '#/components/responses/Generic503'
components:
  responses:
    Generic504:
      description: Request time exceeded. If it happens repeatedly, consider reducing the request complexity
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 504
            code: TIMEOUT
            message: Request timeout exceeded. Try later
    Generic422:
      description: Unprocessable Content
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          examples:
            GENERIC_422_DEVICE_IDENTIFIERS_MISMATCH:
              description: Inconsistency between device identifiers not pointing to the same device
              value:
                status: 422
                code: DEVICE_IDENTIFIERS_MISMATCH
                message: Provided device identifiers are not consistent.
            GENERIC_422_DEVICE_NOT_APPLICABLE:
              description: Service is not available for the provided device
              value:
                status: 422
                code: DEVICE_NOT_APPLICABLE
                message: The service is not available for the provided device.
            GENERIC_422_UNIDENTIFIABLE_DEVICE:
              description: phone number not available neither from "phoneNumber" or from the access token.
              value:
                status: 422
                code: UNIDENTIFIABLE_DEVICE
                message: phone number not defined
    Generic409:
      description: Conflict
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          examples:
            GENERIC_409_ABORTED:
              description: Concurrency of processes of the same nature/scope
              value:
                status: 409
                code: ABORTED
                message: Concurrency conflict.
            GENERIC_409_ALREADY_EXISTS:
              description: Trying to create an existing resource
              value:
                status: 409
                code: ALREADY_EXISTS
                message: The resource that a client tried to create already exists.
            GENERIC_409_CONFLICT:
              description: Duplication of an existing resource
              value:
                status: 409
                code: CONFLICT
                message: A specified resource duplicate entry found.
    Generic403:
      description: Client does not have sufficient permission
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          examples:
            PermissionDenied:
              value:
                status: 403
                code: PERMISSION_DENIED
                message: Client does not have sufficient permissions to perform this action
            InvalidTokenContext:
              value:
                status: 403
                code: INVALID_TOKEN_CONTEXT
                message: PhoneNumber parameter doesn't match the value from the access token context
    Generic415:
      description: Unsupported Media Type
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          examples:
            GENERIC_415_UNSUPPORTED_MEDIA_TYPE:
              description: Payload format of the request is in an unsupported format by the Server.
              value:
                status: 415
                code: UNSUPPORTED_MEDIA_TYPE
                message: The server refuses to accept the request because the payload format is in an unsupported format.
    Generic404:
      description: The specified resource was not found
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 404
            code: CALL_FORWARDING.UNKNOWN_PHONE_NUMBER
            message: Call forwarding check can't be done because the phone number is unknown
    Generic500:
      description: Server error
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 500
            code: INTERNAL
            message: Server error
    Generic503:
      description: Service unavailable. Typically the server is down
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 503
            code: UNAVAILABLE
            message: Service unavailable
    Generic400:
      description: Problem with the client request
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 400
            code: INVALID_ARGUMENT
            message: Client specified an invalid argument, request body or query param
    Generic429:
      description: Too Many Requests
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          examples:
            GENERIC_429_QUOTA_EXCEEDED:
              description: Request is rejected due to exceeding a business quota limit.
              value:
                status: 429
                code: QUOTA_EXCEEDED
                message: Either out of resource quota or reaching rate limiting.
            GENERIC_429_TOO_MANY_REQUESTS:
              description: API Server request limit is overpassed
              value:
                status: 429
                code: TOO_MANY_REQUESTS
                message: Either out of resource quota or reaching rate limiting.
    Generic401:
      description: Authentication problem with the client request
      headers:
        x-correlator:
          $ref: '#/components/headers/x-correlator'
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/ErrorInfo'
          example:
            status: 401
            code: UNAUTHENTICATED
            message: Request not authenticated due to missing, invalid, or expired credentials
  schemas:
    ErrorInfo:
      description: error information
      type: object
      required:
      - status
      - code
      - message
      properties:
        status:
          type: integer
          description: HTTP status code returned along with this error response
        code:
          type: string
          description: Code given to this error
        message:
          type: string
          description: Detailed error description
    PhoneNumber:
      description: A public identifier addressing a telephone subscription. In mobile networks it corresponds to the MSISDN (Mobile Station International Subscriber Directory Number). In order to be globally unique it has to be formatted in international format, according to E.164 standard, prefixed with '+'.
      type: string
      pattern: ^\+[1-9][0-9]{4,14}$
      example: '+123456789'
    CreateCallForwardingSignal:
      description: resource containing the phone number (PhoneNumber) regarding which the Call Forwarding Service must be checked
      type: object
      properties:
        phoneNumber:
          $ref: '#/components/schemas/PhoneNumber'
    UnconditionalCallForwardingSignal:
      description: resource containing the information about the Unconditional Call Forwarding Service for the given phone number (PhoneNumber)
      type: object
      properties:
        active:
          type: boolean
          description: Indicates if the unconditional call forwarding service is active.
  parameters:
    x-correlator:
      name: x-correlator
      in: header
      description: Correlation id for the different services
      schema:
        type: string
  headers:
    x-correlator:
      description: Correlation id for the different services
      schema:
        type: string
  securitySchemes:
    openId:
      description: to support Consent Management
      type: openIdConnect
      openIdConnectUrl: https://example.com/.well-known/openid-configuration
externalDocs:
  description: Product documentation at CAMARA
  url: https://github.com/camaraproject/CallForwardingSignal