Assigning number to AutoAttendant Resource Account results in "Service is unavailable. Please try again"

Hi Ryan,

Given that you have already verified your resource account licensing, permissions, and attempted both the Teams Admin Center and PowerShell, this persistent "Service is unavailable" error typically points to a backend issue or an inventory state inconsistency on Microsoft's service number infrastructure.

Because this is a server-side limitation that cannot be bypassed via admin configurations, you will need to open a support request with Microsoft.

I believe the best next step for your IT admin is creating a support ticket through the Microsoft 365 Admin Center > Support > Help & Support to have Microsoft Support agent assist you in this regard

Turn off the "Support Assistant" feature.  

Use the keyword "Support" to quickly bypass automated suggestions > Select Contact Support.  

In the ticket description, please clearly describe the issue, including any error messages or codes and the steps you’ve already tried. You can also attach screenshots or screen recordings. Additionally, sharing your preferred contact times may help the support team handle the case more efficiently.   

A technical support engineer can perform a remote session to investigate the situation, verify the backend configurations, and run any necessary synchronization tools to resolve the problem. If the issue requires further attention, they can escalate it to a specialized team for deeper analysis.    

If you have any questions or need further support, please don’t hesitate to reach out at any time. 

Thank you for your patience and understanding. 

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