diff --git a/documentation/API-design-guidelines.md b/documentation/API-design-guidelines.md
index cd30bd4c..e36b0757 100644
--- a/documentation/API-design-guidelines.md
+++ b/documentation/API-design-guidelines.md
@@ -793,21 +793,21 @@ In the following, we elaborate on the existing client errors. In particular, we
 
 NOTE: The rest of Error status defined in section 6.1. will be documented depending on specific considerations within a given WG.
 
-### 6.2 Error Responses - Device Object
+### 6.2 Error Responses - Device Object/Phone Number
 
-This section is focused in the guidelines about error responses around the concept of `device` object.
+This section is focused in the guidelines about error responses around the concept of `device` object or `phoneNumber` field.
 
 The Following table compiles the guidelines to be adopted:
 
 | **Case #** | **Description**                                                            | **Error status** |         **Error code**         | **Message example**                                      |
 |:----------:|:---------------------------------------------------------------------------|:----------------:|:------------------------------:|:---------------------------------------------------------|
 |     0      | The request body does not comply with the schema                           |       400        |        INVALID_ARGUMENT        | Request body does not comply with the schema.            |
-|     1      | None of the provided device identifiers is supported by the implementation |       422        | UNSUPPORTED_DEVICE_IDENTIFIERS | phoneNumber is required.                                 |
-|     2      | Some identifier cannot be matched to a device                              |       404        |        DEVICE_NOT_FOUND        | Device identifier not found.                             |  
-|     3      | Device identifiers mismatch                                                |       422        |  DEVICE_IDENTIFIERS_MISMATCH   | Provided device identifiers are not consistent.          |
-|     4      | Invalid access token context                                               |       403        |     INVALID_TOKEN_CONTEXT      | Device identifiers are not consistent with access token. |
-|     5      | Service not applicable to the device                                       |       422        |     DEVICE_NOT_APPLICABLE      | The service is not available for the provided device.    |
-|     6      | The device identifier is not included in the request and the device information cannot be derived from the 3-legged access token |       422        |     UNIDENTIFIABLE_DEVICE      | The device cannot be identified. |
+|     1      | None of the provided device identifiers is supported by the implementation |       422        |     UNSUPPORTED_IDENTIFIER     | The identifier provided is not supported.                                 |
+|     2      | Some identifier cannot be matched to a device                              |       404        |      IDENTIFIER_NOT_FOUND      | Device identifier not found.                             |  
+|     3      | Device identifiers mismatch                                                |       422        |       IDENTIFIER_MISMATCH      | Provided identifiers are not consistent.          |
+|     4      | An explicit identifier is provided when an API subject has already been identified from the access token |       422        |     UNNECESSARY_IDENTIFIER      | The device is already identified by the access token. |
+|     5      | Service not applicable for the provided identifier                         |       422        |     SERVICE_NOT_APPLICABLE     | The service is not available for the provided identifier.    |
+|     6      | An identifier is not included in the request and the API subject cannot be derived from the 3-legged access token |       422       |      MISSING_IDENTIFIER      | The device cannot be identified. |