Update calling-chat.md

Author: tomkau

articles/communication-services/concepts/interop/calling-chat.md

@@ -13,9 +13,11 @@ ms.subservice: teams-interop
 # Teams Interoperability: Calling and chat
 
 > [!IMPORTANT]
-> Calling and chat interoperability is in private preview, and restricted to selected Azure Communication Services early adopters.
+> Calling and chat interoperability is in private preview, and restricted to a limited number of Azure Communication Services early adopters. You can [submit this form to request participation in the preview](https://forms.office.com/r/F3WLqPjw0D) and we will review your scenario(s) and evaluate your participation in the preview.
 >
 > Private Preview APIs and SDKs are provided without a service-level agreement, and are not appropriate for production workloads and should only be used with test users and test data. Certain features might not be supported or might have constrained capabilities. For more information, see [Supplemental Terms of Use for Microsoft Azure Previews](https://azure.microsoft.com/support/legal/preview-supplemental-terms/).
+> 
+> For support, questions or to provide feedback or report issues, please use the [Teams Interop ad hoc calling and chat channel](https://teams.microsoft.com/l/channel/19%3abfc7d5e0b883455e80c9509e60f908fb%40thread.tacv2/Teams%2520Interop%2520ad%2520hoc%2520calling%2520and%2520chat?groupId=d78f76f3-4229-4262-abfb-172587b7a6bb&tenantId=72f988bf-86f1-41af-91ab-2d7cd011db47). You must be a member of the Azure Communication Service TAP team.
 
 As part of this preview, the Azure Communication Services SDKs can be used to build applications that enable bring your own identity (BYOI) users to start 1:1 calls or 1:n chats with Teams users. [Standard ACS pricing](https://azure.microsoft.com/pricing/details/communication-services/) applies to these users, but there's no extra fee for the interoperability capability itself.