openapi: 3.0.0
info:
  title: 3gpp-monitoring-event
  version: "1.1.0.alpha-1"
externalDocs:
  description: 3GPP TS 29.122 V16.1.0 T8 reference point for Northbound APIs
  url: 'http://www.3gpp.org/ftp/Specs/archive/29_series/29.122/'
security:
  - {}
  - oAuth2ClientCredentials: []
servers:
  - url: '{apiRoot}/3gpp-monitoring-event/v1'
    variables:
      apiRoot:
        default: https://example.com
        description: apiRoot as defined in subclause 5.2.4 of 3GPP TS 29.122.
paths:
  /{scsAsId}/subscriptions:
    get:
      summary: read all of the active subscriptions for the SCS/AS
      tags:
        - MonitoringEvent API SCS/AS level GET Operation
      parameters:
        - name: scsAsId
          in: path
          description: Identifier of the SCS/AS
          required: true
          schema:
            type: string
      responses:
        '200':
          description: OK (Successful get all of the active subscriptions for the SCS/AS)
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/MonitoringEventSubscription'
                minItems: 0
                description: Monitoring event subscriptions
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '406':
          $ref: 'TS29122_CommonData.yaml#/components/responses/406'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    post:
      summary: Creates a new subscription resource for monitoring event notification
      tags:
        - MonitoringEvent API Subscription level POST Operation
      parameters:
        - name: scsAsId
          in: path
          description: Identifier of the SCS/AS
          required: true
          schema:
            type: string
      requestBody:
        description: Subscription for notification about monitoring event
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MonitoringEventSubscription'
      callbacks:
        notificationDestination:
          '{request.body#/notificationDestination}':
            post:
              requestBody:  # contents of the callback message
                required: true
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/MonitoringNotification'
              responses:
                '204':
                  description: No Content (successful notification)
                '400':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/400'
                '401':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/401'
                '403':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/403'
                '404':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/404'
                '411':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/411'
                '413':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/413'
                '415':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/415'
                '429':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/429'
                '500':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/500'
                '503':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/503'
                default:
                  $ref: 'TS29122_CommonData.yaml#/components/responses/default'
      responses:
        '201':
          description: Created (Successful creation of subscription)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MonitoringEventSubscription'
          headers:
            Location:
              description: 'Contains the URI of the newly created resource'
              required: true
              schema:
                type: string
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

  /{scsAsId}/subscriptions/{subscriptionId}:
    get:
      summary: read an active subscriptions for the SCS/AS and the subscription Id
      tags:
        - MonitoringEvent API Subscription level GET Operation
      parameters:
        - name: scsAsId
          in: path
          description: Identifier of the SCS/AS
          required: true
          schema:
            type: string
        - name: subscriptionId
          in: path
          description: Identifier of the subscription resource
          required: true
          schema:
            type: string
      responses:
        '200':
          description: OK (Successful get the active subscription)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MonitoringEventSubscription'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '406':
          $ref: 'TS29122_CommonData.yaml#/components/responses/406'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    put:
      summary: Updates/replaces an existing subscription resource
      tags:
        - MonitoringEvent API subscription level PUT Operation
      parameters:
        - name: scsAsId
          in: path
          description: Identifier of the SCS/AS
          required: true
          schema:
            type: string
        - name: subscriptionId
          in: path
          description: Identifier of the subscription resource
          required: true
          schema:
            type: string
      requestBody:
        description: Parameters to update/replace the existing subscription
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/MonitoringEventSubscription'
      responses:
        '200':
          description: OK (Successful update of the subscription)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MonitoringEventSubscription'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    delete:
      summary: Deletes an already existing monitoring event subscription
      tags:
        - MonitoringEvent API Subscription level DELETE Operation
      parameters:
        - name: scsAsId
          in: path
          description: Identifier of the SCS/AS
          required: true
          schema:
            type: string
        - name: subscriptionId
          in: path
          description: Identifier of the subscription resource
          required: true
          schema:
            type: string
      responses:
        '204':
          description: No Content (Successful deletion of the existing subscription)
        '200':
          description: OK (Successful deletion of the existing subscription)
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/MonitoringEventReport'
                minItems: 1
                description: The subscription was terminated successfully, the monitoring event report(s) shall be included if received.
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'
components:
  securitySchemes:
    oAuth2ClientCredentials:
      type: oauth2
      flows:
        clientCredentials:
          tokenUrl: '{tokenUrl}'
          scopes: {}
  schemas: 
    MonitoringEventSubscription:
      type: object
      properties:
        self:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Link'
        supportedFeatures:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
        externalId:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/ExternalId'
        msisdn:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Msisdn'
        externalGroupId:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/ExternalGroupId'
        addExtGroupId:
          type: array
          items:
            $ref: 'TS29122_CommonData.yaml#/components/schemas/ExternalGroupId'
          minItems: 2
        ipv4Addr:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Ipv4Addr'
        ipv6Addr :
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Ipv6Addr'
        notificationDestination:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Link'
        requestTestNotification:
          type: boolean
          description: Set to true by the SCS/AS to request the SCEF to send a test notification as defined in subclause 5.2.5.3. Set to false or omitted otherwise.
        websockNotifConfig:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/WebsockNotifConfig'
        monitoringType:
          $ref: '#/components/schemas/MonitoringType'
        maximumNumberOfReports:
          type: integer
          minimum: 1
          description: Identifies the maximum number of event reports to be generated by the HSS, MME/SGSN as specified in subclause 5.6.0 of 3GPP TS 23.682 [2].
        monitorExpireTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTime'
        groupReportGuardTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        maximumDetectionTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        reachabilityType:
          $ref: '#/components/schemas/ReachabilityType'
        maximumLatency:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        maximumResponseTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        suggestedNumberOfDlPackets:
          type: integer
          minimum: 0
          description: If "monitoringType" is "UE_REACHABILITY", this parameter may be included to identify the number of packets that the serving gateway shall buffer in case that the UE is not reachable.
        idleStatusIndication:
          type: boolean
          description: If "monitoringType" is set to "UE_REACHABILITY" or "AVAILABILITY_AFTER_DDN_FAILURE", this parameter may be included to indicate the notification of when a UE, for which PSM is enabled, transitions into idle mode. -  "true"  indicate enabling of notification -  "false"  indicate no need to notify Default  "false".
        locationType:
          $ref: '#/components/schemas/LocationType'
        accuracy:
          $ref: '#/components/schemas/Accuracy'
        minimumReportInterval:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        associationType:
          $ref: '#/components/schemas/AssociationType'
        plmnIndication:
          type: boolean
          description: If "monitoring-Type" is "ROAMING_STATUS", this parameter may be included to indicate the notification of UE's Serving PLMN ID. -  "true"  The value shall be used to indicate enabling of notification; -  "false"  The value shall be used to indicate disabling of notification.  Default  "false".
        locationArea:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/LocationArea'
        LocationArea5G:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/LocationArea5G'
        monitoringEventReport:
          $ref: '#/components/schemas/MonitoringEventReport'
      required:
        - notificationDestination
        - monitoringType
      anyOf:
        - required: [maximumNumberOfReports]
        - required: [monitorExpireTime]
    MonitoringNotification:
      type: object
      properties:
        subscription:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Link'
        configResults:
          type: array
          items:
            $ref: 'TS29122_CommonData.yaml#/components/schemas/ConfigResult'
          minItems: 1
          description: Each element identifies a notification of grouping configuration result.
        monitoringEventReports:
          type: array
          items:
            $ref: '#/components/schemas/MonitoringEventReport'
          minItems: 1
          description: Monitoring event reports.
        cancelInd:
          type: boolean
          description: Indicates whether to request to cancel the corresponding monitoring subscription. Set to false or omitted otherwise.
      required:
        - subscription
    MonitoringEventReport:
      type: object
      properties:
        imeiChange:
          $ref: '#/components/schemas/AssociationType'
        externalId:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/ExternalId'
        idleStatusInfo:
          $ref: '#/components/schemas/IdleStatusInfo'
        locationInfo:
          $ref: '#/components/schemas/LocationInfo'
        lossOfConnectReason:
          type: integer
          description: If "monitoring-Type" is "LOSS_OF_CONNECTIVITY", this parameter shall be included if available to identify the reason why loss of connectivity is reported. Refer to 3GPP TS 29.336 [11] Subclause 8.4.58.
        maxUEAvailabilityTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTime'
        msisdn:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Msisdn'
        monitoringType:
          $ref: '#/components/schemas/MonitoringType'
        uePerLocationReport:
          $ref: '#/components/schemas/UePerLocationReport'
        plmnId:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/PlmnId'
        reachabilityType:
          $ref: '#/components/schemas/ReachabilityType'
        roamingStatus:
          type: boolean
          description: If "monitoringType" is "ROAMING_STATUS", this parameter shall be set to "true" if the UE is on roaming status. Set to false or omitted otherwise.
        failureCause:
          $ref: '#/components/schemas/FailureCause'
        eventTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTime'
        pdnConnInfo:
          $ref: '#/components/schemas/PdnConnectionInformation'
      required:
        - monitoringType
    IdleStatusInfo:
      type: object
      properties:
        activeTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        edrxCycleLength:
          format: float
          type: number
          minimum: 0
        suggestedNumberOfDlPackets:
          type: integer
          minimum: 0
          description: Identifies the number of packets shall be buffered in the serving gateway. It shall be present if the idle status indication is requested by the SCS/AS with "idleStatusIndication" in the "monitoringEventSubscription" sets to "true".
        idleStatusTimestamp:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTime'
        periodicAUTimer:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
    UePerLocationReport:
      type: object
      properties:
        ueCount:
          type: integer
          minimum: 0
          description: Identifies the number of UEs.
        externalIds:
          type: array
          items:
            $ref: 'TS29122_CommonData.yaml#/components/schemas/ExternalId'
          minItems: 1
          description: Each element uniquely identifies a user.
        msisdns:
          type: array
          items:
            $ref: 'TS29122_CommonData.yaml#/components/schemas/Msisdn'
          minItems: 1
          description: Each element identifies the MS internal PSTN/ISDN number allocated for a UE.
      required:
        - ueCount
    LocationInfo:
      type: object
      properties:
        ageOfLocationInfo:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationMin'
        cellId:
          type: string
          description: Indicates the Cell Global Identification of the user which identifies the cell the UE is registered.
        enodeBId:
          type: string
          description: Indicates the eNodeB in which the UE is currently located.
        routingAreaId:
          type: string
          description: Identifies the Routing Area Identity of the user where the UE is located.
        trackingAreaId:
          type: string
          description: Identifies the Tracking Area Identity of the user where the UE is located.
        plmnId:
          type: string
          description: Identifies the PLMN Identity of the user where the UE is located.
        twanId:
          type: string
          description: Identifies the TWAN Identity of the user where the UE is located.
        geographicArea:
          $ref: 'TS29572_Nlmf_Location.yaml#/components/schemas/GeographicArea'
    FailureCause:
      type: object
      properties:
        bssgpCause:
          type: integer
          description: Identifies a non-transparent copy of the BSSGP cause code. Refer to 3GPP TS 29.128 [12].
        causeType:
          type: integer
          description: Identify the type of the S1AP-Cause. Refer to 3GPP TS 29.128 [12].
        gmmCause:
          type: integer
          description: Identifies a non-transparent copy of the GMM cause code. Refer to 3GPP TS 29.128 [12].
        ranapCause:
          type: integer
          description: Identifies a non-transparent copy of the RANAP cause code. Refer to 3GPP TS 29.128 [12].
        ranNasCause:
          type: string
          description: Indicates RAN and/or NAS release cause code information, TWAN release cause code information or untrusted WLAN release cause code information. Refer to 3GPP TS 29.214 [10].
        s1ApCause:
          type: integer
          description: Identifies a non-transparent copy of the S1AP cause code. Refer to 3GPP TS 29.128 [12].
        smCause:
          type: integer
          description: Identifies a non-transparent copy of the SM cause code. Refer to 3GPP TS 29.128 [12].
    PdnConnectionInformation:
      type: object
      properties:
        status:
          $ref: '#/components/schemas/PdnConnectionStatus'
        apn:
          type: string
          description: Identify the APN, it is depending on the SCEF local configuration whether or not this attribute is sent to the SCS/AS.
        pdnType:
          $ref: '#/components/schemas/PdnType'
        interfaceInd:
          $ref: '#/components/schemas/InterfaceIndication'
        ipv4Addr:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Ipv4Addr'
        ipv6Addr:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Ipv6Addr'
      required:
        - status
        - pdnType
      anyOf:
        - required: [ipv4Addr]
        - required: [ipv6Addr]
    MonitoringType:
      anyOf:
      - type: string
        enum:
          - LOSS_OF_CONNECTIVITY
          - UE_REACHABILITY
          - LOCATION_REPORTING
          - CHANGE_OF_IMSI_IMEI_ASSOCIATION
          - ROAMING_STATUS
          - COMMUNICATION_FAILURE
          - AVAILABILITY_AFTER_DDN_FAILURE
          - NUMBER_OF_UES_IN_AN_AREA
          - PDN_CONNECTIVITY_STATUS
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - LOSS_OF_CONNECTIVITY: The SCS/AS requests to be notified when the 3GPP network detects that the UE is no longer reachable for signalling or user plane communication
        - UE_REACHABILITY: The SCS/AS requests to be notified when the UE becomes reachable for sending either SMS or downlink data to the UE
        - LOCATION_REPORTING: The SCS/AS requests to be notified of the current location or the last known location of the UE
        - CHANGE_OF_IMSI_IMEI_ASSOCIATION: The SCS/AS requests to be notified when the association of an ME (IMEI(SV)) that uses a specific subscription (IMSI) is changed
        - ROAMING_STATUS: The SCS/AS queries the UE's current roaming status and requests to get notified when the status changes
        - COMMUNICATION_FAILURE: The SCS/AS requests to be notified of communication failure events
        - AVAILABILITY_AFTER_DDN_FAILURE: The SCS/AS requests to be notified when the UE has become available after a DDN failure
        - NUMBER_OF_UES_IN_AN_AREA: The SCS/AS requests to be notified the number of UEs in a given geographic area 
        - PDN_CONNECTIVITY_STATUS: The SCS/AS requests to be notified when the 3GPP network detects that the UE’s PDN connection is set up or torn down
    ReachabilityType:
      anyOf:
      - type: string
        enum:
          - SMS 
          - DATA
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - SMS : The SCS/AS requests to be notified when the UE becomes reachable for sending SMS to the UE
        - DATA: The SCS/AS requests to be notified when the UE becomes reachable for sending downlink data to the UE
    LocationType:
      anyOf:
      - type: string
        enum:
          - CURRENT_LOCATION
          - LAST_KNOWN_LOCATION
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - CURRENT_LOCATION: The SCS/AS requests to be notified for current location
        - LAST_KNOWN_LOCATION: The SCS/AS requests to be notified for last known location
    AssociationType:
      anyOf:
      - type: string
        enum:
          - IMEI
          - IMEISV
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - IMEI: The value shall be used when the change of IMSI-IMEI association shall be detected
        - IMEISV: The value shall be used when the change of IMSI-IMEISV association shall be detected
    Accuracy:
      anyOf:
      - type: string
        enum:
          - CGI_ECGI
          - ENODEB
          - TA_RA
          - PLMN
          - TWAN_ID
          - GEO_AREA
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - CGI_ECGI: The SCS/AS requests to be notified at cell level location accuracy.
        - ENODEB: The SCS/AS requests to be notified at eNodeB level location accuracy.
        - TA_RA: The SCS/AS requests to be notified at TA/RA level location accuracy.
        - PLMN: The SCS/AS requests to be notified at PLMN level location accuracy.
        - TWAN_ID: The SCS/AS requests to be notified at TWAN identifier level location accuracy.
        - GEO_AREA: The SCS/AS requests to be notified of the geographical area accuracy.
    PdnConnectionStatus:
      anyOf:
      - type: string
        enum:
          - CREATED
          - RELEASED
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - CREATED: The PDN connection is created.
        - RELEASED: The PDN connection is released.
    PdnType:
      anyOf:
      - type: string
        enum:
          - IP
          - NON_IP
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - IP: PDN connection of IP type.
        - NON_IP: PDN connection of non-IP type.
    InterfaceIndication:
      anyOf:
      - type: string
        enum:
          - EXPOSURE_FUNCTION
          - PDN_GATEWAY
      - type: string
        description: >
          This string provides forward-compatibility with future
          extensions to the enumeration but is not used to encode
          content defined in the present version of this API.
      description: >
        Possible values are
        - EXPOSURE_FUNCTION: SCEF is used for the PDN connection towards the SCS/AS.
        - PDN_GATEWAY: PDN gateway is used for the PDN connection towards the SCS/AS.