Update connected-network-type-subscriptions.yaml

code/API_definitions/connected-network-type-subscriptions.yaml

@@ -53,16 +53,42 @@ info:
       Developers may provide a callback URL on which notifications regarding connected network type can be received from the service provider.
       If an event occurs the application will send events to the provided webhook - 'sink'._
 
-    # Authorization and authentication
+    # Further info and support
+
+    (FAQs will be added in a later version of the documentation)
+
+    ## 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 API Provider, 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.
 
-    # Further info and support
+    ## Identifying the device from the access token
 
-    (FAQs will be added in a later version of the documentation)
+    This API requires the API consumer to identify a device as the subject of the API as follows:
+    - When the API is invoked using a two-legged access token, the subject will be identified from the optional `device` object, which therefore MUST be provided.
+
+    - When a three-legged access token is used however, this optional identifier MUST NOT be provided, as the subject will be uniquely identified from the access token.
+
+    This approach simplifies API usage for API consumers using a three-legged access token to invoke the API by relying on the information that is associated with the access token and was identified during the authentication process.
+
+    ### Error handling:
+    - If the subject cannot be identified from the access token and the optional `device` object is not included in the request, then the server will return an error with the `422 MISSING_IDENTIFIER` error code.
+
+    - If the subject can be identified from the access token and the optional `device` object is also included in the request, then the server will return an error with the `422 UNNECESSARY_IDENTIFIER` error code. This will be the case even if the same device is identified by these two methods, as the server is unable to make this comparison.
+
+    ## Multi-SIM scenario handling
+
+    In multi-SIM scenarios where more than one mobile device is associated with a phone number (e.g. a smartphone with an associated smartwatch), it might not be possible to uniquely identify from that phone number the device for which connected network type notifications should be generated. If the phone number is used as the device identifier when creating a subscription in a multi-SIM scenario, the API may:
+    - respond with an error, or
+    - generate network type change notifications for the multi-SIM group as a whole, or
+    - generate network type change notifications for a single device in the multi-SIM group, which may not be the intended device.
+
+    Possible solutions in such a scenario include:
+    - Using the authorisation code flow to obtain an access token, which will automatically identify the intended device
+    - Identifying the intended device from a unique identifier for that device, such as its source IP address and port
+    - Check with the SIM provider whether a unique "secondary" phone number is already associated with each device, and use the secondary phone number to identify the intended device if available.
 
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