Assign Teams Phone Mobile number to user

I am piloting Teams Phone Mobile with Verizon. I have everything setup on Verizon's side. Now I want to assign this number to a user.

First, I tried using admin center. I went to Voice > Phone Numbers > chose the phone number > Edit. However, when I search for users, I can't find any users. The user I'm testing it on is in Teams Only mode. 

So, I tried assigning the number with Powershell as described here: https://learn.microsoft.com/en-us/microsoftteams/assign-change-or-remove-a-phone-number-for-a-user . I used this command: Set-CsPhoneNumberAssignment -Identity <user> -PhoneNumber <phone number> -PhoneNumberType OCMobile

I got this: 

Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberAssignment : Could not resolve phoneNumberType 'OCMobile'.
Available phoneNumberType values are 'DirectRouting', 'CallingPlan', 'OperatorConnect'.
At C:\Program Files\WindowsPowerShell\Modules\MicrosoftTeams\4.5.0\custom\PsExt\Merged_custom_PsExt.ps1:6216 char:9
+ Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberA ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: ({ Identity = ds...iceEnabled = }:<>f__AnonymousType100`5) [Set-CsPho
neNumberAssignment_Set], Exception
+ FullyQualifiedErrorId : InvalidInput,Microsoft.Teams.ConfigAPI.Cmdlets.Generated.Cmdlets.SetCsPhoneNumberAssignm
ent_Set

So, I tried this: 

Set-CsPhoneNumberAssignment -Identity email address removed for privacy reasons -PhoneNumber "+17175758181" -PhoneNumberType OperatorConnect

Then I got this: 

Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberAssignment : The user '***@***' is not found
At C:\Program Files\WindowsPowerShell\Modules\MicrosoftTeams\4.5.0\custom\PsExt\Merged_custom_PsExt.ps1:6216 char:9
+ Microsoft.Teams.ConfigAPI.Cmdlets.internal\Set-CsPhoneNumberA ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: ({ Identity = ds...iceEnabled = }:<>f__AnonymousType100`5) [Set-CsPho
neNumberAssignment_Set], Exception
+ FullyQualifiedErrorId : NotFound,Microsoft.Teams.ConfigAPI.Cmdlets.Generated.Cmdlets.SetCsPhoneNumberAssignment_
Set

Any suggestions on how to resolve this?