Merge pull request #268114 from rcdun/1321970_maximum_domain_length

1321970 Document overall length limit for Direct Routing customer sub…

Author: prmerger-automator[bot]

articles/communications-gateway/configure-test-customer-teams-direct-routing.md

@@ -35,12 +35,14 @@ You must be able to sign in to the Microsoft 365 admin center for your test cust
 
 ## Choose a DNS subdomain label to use to identify the customer
 
-Azure Communications Gateway has per-region domain names. You need to set up subdomains of these domain names for your test customer.  Microsoft Phone System and Azure Communications Gateway use this subdomain to match calls to tenants.
+Azure Communications Gateway has per-region domain names. You need to set up subdomains of these domain names for your test customer. Microsoft Phone System and Azure Communications Gateway use these subdomains to match calls to tenants.
 
 1. Choose a DNS label to identify the test customer.
-    * The label can be up to 10 characters in length and can only contain letters, numbers, underscores, and dashes.
+    * The label must be up to **eight** characters in length and can only contain letters, numbers, underscores, and dashes.
     * You must not use wildcard subdomains or subdomains with multiple labels.
     * For example, you could allocate the label `test`.
+    > [!IMPORTANT]
+    > The full customer subdomains (including the per-region domain names) must be a maximum of 48 characters. Microsoft Entra ID does not support domain names of more than 48 characters. For example,  the customer subdomain `contoso1.1-r1.a1b2c3d4e5f6g7h8.commsgw.azure.com` is 48 characters.
 1. Use this label to create a subdomain of each per-region domain name for your Azure Communications Gateway.
 1. Make a note of the label you choose and the corresponding subdomains.
 
@@ -62,8 +64,6 @@ If you allocate the label `test`, this label combined with the per-region domain
 * `test.r1.<deployment_id>.commsgw.azure.com`
 * `test.r2.<deployment_id>.commsgw.azure.com`
 
-
-
 > [!TIP]
 > Lab deployments have one per-region domain name. Your test customer therefore also only has one customer-specific per-region domain name.
 

articles/communications-gateway/interoperability-teams-direct-routing.md

@@ -60,12 +60,14 @@ Each of your customers needs _customer subdomains_ of these per-region domains.
 
 For each customer, you must:
 
-- Choose a suitable subdomain. The label for the subdomain must:
-    - Contain only letters, numbers, underscores and dashes.
-    - Be up to 63 characters in length.
+1. Choose a suitable subdomain. The label for the subdomain must:
+    - Contain only letters, numbers, underscores, and dashes.
+    - Be up to **eight** characters in length.
     - Not contain a wildcard or multiple labels separated by `.`.
-- Configure Azure Communications Gateway with this information, as part of "account" configuration available over the Provisioning API.
-- Liaise with the customer to update their tenant with the appropriate subdomain, by following the [Microsoft Teams documentation for registering subdomain names in customer tenants](/microsoftteams/direct-routing-sbc-multiple-tenants#register-a-subdomain-name-in-a-customer-tenant).
+    > [!IMPORTANT]
+    > The full customer subdomain (including the regional subdomains and the base domain) must be a maximum of 48 characters. Microsoft Entra ID does not support domain names of more than 48 characters. For example, the customer subdomain `contoso1.1-r1.a1b2c3d4e5f6g7h8.commsgw.azure.com` is 48 characters.
+2. Configure Azure Communications Gateway with this information, as part of "account" configuration available over the Provisioning API.
+3. Liaise with the customer to update their tenant with the appropriate subdomain, by following the [Microsoft Teams documentation for registering subdomain names in customer tenants](/microsoftteams/direct-routing-sbc-multiple-tenants#register-a-subdomain-name-in-a-customer-tenant).
 
 As part of arranging updates to customer tenants, you must create DNS records containing a verification code (provided by Microsoft 365 when the customer updates their tenant with the domain name) on a DNS server that you control. These records allow Microsoft 365 to verify that the customer tenant is authorized to use the domain name. Azure Communications Gateway provides the DNS server that you must use. You must obtain the verification code from the customer and upload it with Azure Communications Gateway's Provisioning API to generate the DNS TXT records that verify the domain.
 
@@ -95,7 +97,7 @@ The following diagram shows the call flow for an INVITE from a number that hasn'
 
 ## Identifying the customer tenant for Microsoft Phone System
 
-The Microsoft Phone System uses the domains in the Contact header of messages to identify the tenant for each message. Azure Communications Gateway automatically rewrites Contact headers on messages towards the Microsoft Phone System. so that they include the appropriate per-customer domain. This process removes the need for your core network to map between numbers and per-customer domains.
+The Microsoft Phone System uses the domains in the Contact header of messages to identify the tenant for each message. Azure Communications Gateway automatically rewrites Contact headers on messages towards the Microsoft Phone System so that they include the appropriate per-customer domain. This process removes the need for your core network to map between numbers and per-customer domains.
 
 You must provision Azure Communications Gateway with each number assigned to a customer for Direct Routing. This provisioning uses Azure Communications Gateway's Provisioning API.
 
@@ -157,7 +159,7 @@ If you believe that media bypass support (preview) would be useful for your depl
 
 ## Topology hiding with domain delegation
 
-The domain for your Azure Communications Gateway deployment is visible to customer administrators in their Microsoft 365 admin center. By default, each Azure Communications Gateway deployment receives an automatically generated domain name similar to `a1b2c3d4efghij5678.<deployment_id>.commsgw.azure.com`, where `<deployment_id>` is autogenerated and unique to the deployment.
+The domain for your Azure Communications Gateway deployment is visible to customer administrators in their Microsoft 365 admin center. By default, each Azure Communications Gateway deployment receives an automatically generated domain name in the form `<deployment_id>.commsgw.azure.com`, where `<deployment_id>` is autogenerated and unique to the deployment. For example, the domain name might be `a1b2c3d4e5f6g7h8.commsgw.azure.com`.
 
 To hide the details of your deployment, you can configure Azure Communications Gateway to use a subdomain of your own base domain. Customer administrators see subdomains of this domain in their Microsoft 365 admin center. This process uses [DNS delegation with Azure DNS](../dns/dns-domain-delegation.md). You must configure DNS delegation as part of deploying Azure Communications Gateway.