address PR comments

Author: olena-stoliarova

articles/communication-services/concepts/interop/custom-teams-endpoint-authentication-overview.md

@@ -32,8 +32,8 @@ Before we begin:
 
 Steps:
 1. Authenticate Alice using Azure Active Directory: Alice is authenticated using a standard OAuth flow with *Microsoft Authentication Library (MSAL)*. If authentication is successful, the client application receives an Azure AD access token, with a value of 'A1' and an Object ID of an Azure AD user with a value of 'A2'. Tokens are outlined later in this article. Authentication from the developer perspective is explored in this [quickstart](../../quickstarts/manage-teams-identity.md).
-2. Get an access token for Alice: The Fabrikam application by using a custom authentication artifact with value 'B' performs authorization logic to decide whether Alice has permission to exchange the Azure AD access token for an Azure Communication Services access token. After successful authorization, the Fabrikam application performs control plane logic, using artifacts 'A1', 'A2', and 'A3'. Azure Communication Services access token 'D' is generated for Alice within the Fabrikam application. This access token can be used for data plane actions in Azure Communication Services, like Calling. The 'A2' and 'A3' artifacts are passed along with the artifact 'A1' for validation. The validation assures that the Azure AD Token was issued to the expected user. The application and will prevent attackers from using the Azure AD access tokens issued to other applications or other users. For more information on how to get 'A' artifacts, see [Receive the Azure AD user token and object ID via the MSAL library](../../quickstarts/manage-teams-identity.md?pivots=programming-language-csharp#step-1-receive-the-azure-ad-user-token-and-object-id-via-the-msal-library) and [Getting Application ID](../troubleshooting-info.md#getting-application-id).
-3. Call Bob: Alice makes a call to Teams user Bob, with Fabrikam's app. The call takes place via the Calling SDK with an Azure Communication Services access token. Learn more about [developing custom Teams clients](../../quickstarts/voice-video-calling/get-started-with-voice-video-calling-custom-teams-client.md).
+1. Get an access token for Alice: The Fabrikam application by using a custom authentication artifact with value 'B' performs authorization logic to decide whether Alice has permission to exchange the Azure AD access token for an Azure Communication Services access token. After successful authorization, the Fabrikam application performs control plane logic, using artifacts 'A1', 'A2', and 'A3'. Azure Communication Services access token 'D' is generated for Alice within the Fabrikam application. This access token can be used for data plane actions in Azure Communication Services, like Calling. The 'A2' and 'A3' artifacts are passed along with the artifact 'A1' for validation. The validation assures that the Azure AD Token was issued to the expected user. The application and will prevent attackers from using the Azure AD access tokens issued to other applications or other users. For more information on how to get 'A' artifacts, see [Receive the Azure AD user token and object ID via the MSAL library](../../quickstarts/manage-teams-identity.md?pivots=programming-language-csharp#step-1-receive-the-azure-ad-user-token-and-object-id-via-the-msal-library) and [Getting Application ID](../troubleshooting-info.md#getting-application-id).
+1. Call Bob: Alice makes a call to Teams user Bob, with Fabrikam's app. The call takes place via the Calling SDK with an Azure Communication Services access token. Learn more about [developing custom Teams clients](../../quickstarts/voice-video-calling/get-started-with-voice-video-calling-custom-teams-client.md).
 
 Artifacts:
 - Artifact A1
@@ -44,14 +44,15 @@ Artifacts:
 - Artifact A2
   - Type: Object ID of an Azure AD user
   - Source: Fabrikam's Azure AD tenant
-  - Authority: `https://login.microsoftonline.com/<tenant>/` or `https://login.microsoftonline.com/organizations/` (based on your [scenario](../../../active-directory/develop/msal-client-application-configuration.md#authority))
+  - Authority: `https://login.microsoftonline.com/<tenant>/`
 - Artifact A3
   - Type: Azure AD application ID
   - Source: Fabrikam's Azure AD tenant
 - Artifact B
   - Type: Custom Fabrikam authorization artifact (issued either by Azure AD or a different authorization service)
 - Artifact C
-  - Type: Hash-based Message Authentication Code (HMAC) (based on Fabrikam's _`connection string`_)
+  - Type: Azure Communication Services resource authorization artifact. 
+  - Source: "Authorization" HTTP header with either a bearer token for [Azure AD authentication](../authentication#azure-ad-authentication) or a Hash-based Message Authentication Code (HMAC) payload and a signature for [access key-based authentication](../authentication#access-key) (access key or connection string).
 - Artifact D
   - Type: Azure Communication Services access token
   - Audience: _`Azure Communication Services`_ — data plane
@@ -71,8 +72,8 @@ Before we begin:
 
 Steps:
 1. Authenticate Alice using the Fabrikam application: Alice is authenticated through Fabrikam's application. A standard OAuth flow with Microsoft Authentication Library (MSAL) is used. Make sure you configure MSAL with a correct [authority](../../../active-directory/develop/msal-client-application-configuration.md#authority). If authentication is successful, the Contoso client application receives an Azure AD access token with a value of 'A1' and an Object ID of an Azure AD user with a value of 'A2'. Token details are outlined below. Authentication from the developer perspective is explored in this [quickstart](../../quickstarts/manage-teams-identity.md). 
-2. Get an access token for Alice: The Contoso application by using a custom authentication artifact with value 'B' performs authorization logic to decide whether Alice has permission to exchange the Azure AD access token for an Azure Communication Services access token. After successful authorization, the Contoso application performs control plane logic, using artifacts 'A1', 'A2', and 'A3'. An Azure Communication Services access token 'D' is generated for Alice within the Contoso application. This access token can be used for data plane actions in Azure Communication Services, like Calling. The 'A2' and 'A3' artifacts are passed along with the artifact 'A1'. The validation assures that the Azure AD Token was issued to the expected user. The application and will prevent attackers from using the Azure AD access tokens issued to other applications or other users. For more information on how to get 'A' artifacts, see [Receive the Azure AD user token and object ID via the MSAL library](../../quickstarts/manage-teams-identity.md?pivots=programming-language-csharp#step-1-receive-the-azure-ad-user-token-and-object-id-via-the-msal-library) and [Getting Application ID](../troubleshooting-info.md#getting-application-id).
-3. Call Bob: Alice makes a call to Teams user Bob, with Fabrikam's application. The call takes place via the Calling SDK with an Azure Communication Services access token. Learn more about developing custom, Teams apps [in this quickstart](../../quickstarts/voice-video-calling/get-started-with-voice-video-calling-custom-teams-client.md).
+1. Get an access token for Alice: The Contoso application by using a custom authentication artifact with value 'B' performs authorization logic to decide whether Alice has permission to exchange the Azure AD access token for an Azure Communication Services access token. After successful authorization, the Contoso application performs control plane logic, using artifacts 'A1', 'A2', and 'A3'. An Azure Communication Services access token 'D' is generated for Alice within the Contoso application. This access token can be used for data plane actions in Azure Communication Services, like Calling. The 'A2' and 'A3' artifacts are passed along with the artifact 'A1'. The validation assures that the Azure AD Token was issued to the expected user. The application and will prevent attackers from using the Azure AD access tokens issued to other applications or other users. For more information on how to get 'A' artifacts, see [Receive the Azure AD user token and object ID via the MSAL library](../../quickstarts/manage-teams-identity.md?pivots=programming-language-csharp#step-1-receive-the-azure-ad-user-token-and-object-id-via-the-msal-library) and [Getting Application ID](../troubleshooting-info.md#getting-application-id).
+1. Call Bob: Alice makes a call to Teams user Bob, with Fabrikam's application. The call takes place via the Calling SDK with an Azure Communication Services access token. Learn more about developing custom, Teams apps [in this quickstart](../../quickstarts/voice-video-calling/get-started-with-voice-video-calling-custom-teams-client.md).
 
 
 Artifacts: