Update articles/communication-services/concepts/identity-model.md

Author: ttorble

articles/communication-services/concepts/identity-model.md

@@ -23,7 +23,7 @@ Azure Communication Services is an identity-agnostic service, which offers multi
 Azure Communication Services identity model works with two key concepts.
 
 ## User identity / mapping
-When you create a user identity via SDK or REST API, Azure Communication Services creates a unique user identifier. External identifiers such as phone numbers, user/device/application ids, or user names can't be used directly in Azure Communication Services. Instead you have to use the Communication Services identities and maintain a mapping to your own user id system as needed. Creating Azure Communication Service user identities is free and charges are only incurred when the user consumes communication modalities such as a chat or a call. How you use your generated Communication Services identity depends on your scenario. For example, you can map an identity 1:1, 1:N, N:1, or N:N, and you can use it for human users or applications. A user can participate in multiple communication sessions, using multiple devices, simultaneously. Managing a mapping between Azure Communication Services user identities and your own identity system is your responsibility as a developer, and doesn't come built-in. For example, you can add a `CommunicationServicesId` column in your existing user table to store the associated Azure Communication Services identity. A mapping design is described in more detail under [Client-server architecture](#client-server-architecture).
+When you create a user identity via SDK or REST API, Azure Communication Services creates a unique user identifier. External identifiers such as phone numbers, user/device/application IDs, or user names can't be used directly in Azure Communication Services. Instead you have to use the Communication Services identities and maintain a mapping to your own user ID system as needed. Creating Azure Communication Service user identities is free and charges are only incurred when the user consumes communication modalities such as a chat or a call. How you use your generated Communication Services identity depends on your scenario. For example, you can map an identity 1:1, 1:N, N:1, or N:N, and you can use it for human users or applications. A user can participate in multiple communication sessions, using multiple devices, simultaneously. Managing a mapping between Azure Communication Services user identities and your own identity system is your responsibility as a developer, and doesn't come built-in. For example, you can add a `CommunicationServicesId` column in your existing user table to store the associated Azure Communication Services identity. A mapping design is described in more detail under [Client-server architecture](#client-server-architecture).
 
 ## Access tokens 
 After a user identity is created, a user then needs an access token with specific scopes to participate in communications using chat or calls. For example, only a user with a token with the `chat` scope can participate in chat and a user with a token with `voip` scope can participate in a VoIP call. A user can have multiple tokens simultaneously. Azure Communication Services supports multiple token scopes to account for users who require full access vs limited access. Access tokens have the following properties.