For number migrations from Direct Routing to Operator Connect the process has recently changed, you will now need to use the following PowerShell cmdlet which creates a request to release Direct Routing telephone numbers from Microsoft Teams telephone number management inventory.
Numbers to be migrated then can be added using a comma-separated list of numbers, or you can add a range by separating the first and last numbers with a slash (Starting/EndingNumber). The cmdlet is an asynchronous operation and will return an OrderId as output. You can use the below cmdlet to check the status of the OrderId, including any error or warning messages that might result from the operation.
Please note that these commands are only in the new release of PowerShell 6.7.1 which is currently in preview. To download this version please use;
https://www.powershellgallery.com/packages/MicrosoftTeams/6.7.1-preview
This is due to a recent change in the behaviour of Microsoft’s network, where unassigned numbers now enter Microsoft’s number inventory which is flagging as unknown in Gamma’s number status report, which is resulting in the ‘Skype for Business’ error.