Unable to assign a phone number to a bot

I have been trying to assign a number to a bot that I have created so that my bot can answer external calls or forward/transfer accordingly.

I have followed all the instructions from Manage phone numbers for bot.

1. I have created a bot.

2. I have created an application instance (resource account), and used the command

   New-CsOnlineApplicationInstance -UserPrincipalName abcaccount@xyz.onmicrosoft.com -ApplicationId XXXX-XXXX-XXXX-XXX-XXX -DisplayName ABCaccount

This step works fine, I can see the resource account in Teams Admin Center. Here the ApplicationId is the App ID of my bot.

3. I have a free phone number ready to assign.

I am doing this from PowerShell as described in the documentation. But as soon as I try to assign the number I am getting the below error:

Command:

PS C:\WINDOWS\system32> Set-CsPhoneNumberAssignment -Identity abcaccount@xyz.onmicrosoft.com -PhoneNumber +1234567890 -PhoneNumberType CallingPlan

Output:

Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberAssignment : The user 'XXX-XXX-XXX-XXX-XXX' is not found

At C:\Program Files\WindowsPowerShell\Modules\MicrosoftTeams\4.6.0\custom\Merged_custom_PsExt.ps1:1064 char:9

Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberA ...

CategoryInfo   : InvalidOperation: ({ Identity = cs...iceEnabled =  }:f__AnonymousType100`5) [Set-CsPhoneNumberAssignment_Set], Exception
FullyQualifiedErrorId : BadRequest,Microsoft.Teams.ConfigAPI.Cmdlets.Generated.Cmdlets.SetCsPhoneNumberAssignment_Set

I cannot figure out why this error is occurring, I can see the resource account in Team Admin Center.
I also tried assigning a number from the team centre page but I got the same error.

Then I created a new resource account but this time I used the default ID of Auto Attendant as mentioned in New-CsOnlineApplicationInstance. And I was able to assign a number successfully.

It seems that passing the bot app ID to New-CsOnlineApplicationInstance for parameter ApplicationId is somehow causing this issue.

If anyone could help me with some pointers that would be great. Am I doing the right thing here? If not, what's the exact way to assign a number to a bot so that the bot can answer external calls?

Thank you for your help.

Start with the linked Manage phone numbers for bot documentation and compare the New-CsOnlineApplicationInstance and Set-CsPhoneNumberAssignment commands, including the ApplicationId value. Reproduce the error with Microsoft Teams PowerShell 4.6.0, then verify the documented bot application identifier can receive the number and answer external calls.