change domain validation to include entire FQDN

Author: boris-bazilevskiy

articles/communication-services/concepts/telephony/direct-routing-infrastructure.md

@@ -45,7 +45,7 @@ Alternatively, Communication Services direct routing supports a wildcard in the
 
 Customers who already use Office 365 and have a domain registered in Microsoft 365 Admin Center can use SBC FQDN from the same domain.
 
-An example would be using `\*.contoso.com`, which would match the SBC FQDN `sbc.contoso.com`, but wouldn't match with `sbc.test.contoso.com`.
+An example would be using `*.contoso.com`, which would match the SBC FQDN `sbc.contoso.com`, but wouldn't match with `sbc.test.contoso.com`.
 
  >[!NOTE]
  > SBC FQDN in Azure Communication Services direct routing must be different from SBC FQDN in Teams Direct Routing.

articles/communication-services/how-tos/telephony/domain-validation.md

@@ -6,7 +6,7 @@ author: boris-bazilevskiy
 
 ms.service: azure-communication-services
 ms.subservice: pstn
-ms.date: 03/11/2023
+ms.date: 10/02/2023
 ms.topic: how-to
 ms.custom: include file
 ms.author: nikuklic
@@ -18,18 +18,20 @@ This article describes the process of validating domain name ownership by using
 
 A fully qualified domain name (FQDN) consists of two parts: host name and domain name. For example, if your session border controller (SBC) name is `sbc1.contoso.com`, then `sbc1` is the host name and `contoso.com` is the domain name. If an SBC has an FQDN of `acs.sbc1.testing.contoso.com`, then `acs` is the host name and `sbc1.testing.contoso.com` is the domain name.
 
-To use direct routing in Azure Communication Services, you need to validate that you own the domain part of your SBC FQDN. After that, you can configure the SBC FQDN and port number and then create voice routing rules.
+To use direct routing in Azure Communication Services, you need to validate that you own either the domain part of your SBC FQDN, or entire SBC FQDN. After that, you can configure the SBC FQDN and port number and then create voice routing rules.
 
-When you're verifying the domain name portion of the SBC FQDN, keep in mind that the `*.onmicrosoft.com` and `*.azure.com` domain names aren't supported. For example, if you have two domain names, `contoso.com` and `contoso.onmicrosoft.com`, use `sbc.contoso.com` as the SBC name.
+When you're verifying the ownership of the SBC FQDN, keep in mind that the `*.onmicrosoft.com` and `*.azure.com` domain names aren't supported. For example, if you have two domain names, `contoso.com` and `contoso.onmicrosoft.com`, use `sbc.contoso.com` as the SBC name.
+
+Validating domain part makes sense if you plan to add multiple SBCs from the same domain name space. For example if you're using `sbc-eu.contoso.com`, `sbc-us.contoso.com`, and `sbc-af.contoso.com` you can validate `contoso.com` domain once and add SBCs from that domain later without extra validation.
+Validating entire FQDN is helpful if you're a service provider and don't want to validate your base domain ownership with every customer. For example if you're running SBCs `customer1.acs.adatum.biz`, `customer2.acs.adatum.biz`, and `customer3.acs.adatum.biz`, you don't need to validate `acs.adatum.biz` for every Communication resource, instead you validate the entire FQDN each time. This option provides more granular security approach.
 
-If you're using a subdomain, make sure that this subdomain is also added and verified. For example, if you want to use `sbc.acs.contoso.com`, you need to register `acs.contoso.com`.
 
 ## Add a new domain name
 
 1. Open the Azure portal and go to your [Communication Services resource](../../quickstarts/create-communication-resource.md).
 1. On the left pane, under **Voice Calling - PSTN**, select **Direct routing**.
 1. On the **Domains** tab, select **Connect domain**.
-1. Enter the domain part of the SBC FQDN.
+1. Enter the domain part of the SBC FQDN, or entire SBC FQDN.
 1. Reenter the domain name.
 1. Select **Confirm**, and then select **Add**.
 
@@ -42,7 +44,7 @@ If you're using a subdomain, make sure that this subdomain is also added and ver
 
    [![Screenshot of verifying a custom domain.](./media/direct-routing-verify-domain-2.png)](./media/direct-routing-verify-domain-2.png#lightbox)
 
-   It might take up to 30 minutes for a new DNS record to propagate on the internet.
+   It might take up to 30 minutes for a new DNS record to propagate on the Internet.
 
 1. Select **Next**. If you set up everything correctly, **Domain status** should change to **Verified** next to the added domain.
 
@@ -65,4 +67,4 @@ If you want to remove a domain from your Azure Communication Services direct rou
 ### Quickstarts
 
 - [Outbound call to a phone number](../../quickstarts/telephony/pstn-call.md)
-- [Redirect inbound telephony calls with Call Automation](../../quickstarts/call-automation/redirect-inbound-telephony-calls.md)
+- [Redirect inbound telephony calls with Call Automation](../../quickstarts/call-automation/redirect-inbound-telephony-calls.md)