Report Users with NO Alternative Authentication Phone

StuartK73 

Can you try the below script to list all users without alternative auth phone number.

$Result=@()
$users = Get-MsolUser -All
$users | ForEach-Object {
$user = $_
$alternativePhoneNumber = $user.StrongAuthenticationUserDetails.AlternativePhoneNumber
if($alternativePhoneNumber -eq $null) { 
$Result += New-Object PSObject -property @{ 
UserName = $user.DisplayName
UserPrincipalName = $user.UserPrincipalName
}
}
}
$Result | Select UserName,UserPrincipalName

Or you can try below script to list only MFA enabled users without alternative auth phone.

$Result=@()
$users = Get-MsolUser -All | Where {$_.StrongAuthenticationMethods -ne $null -or $_.StrongAuthenticationRequirements.State -ne $nul}
$users | ForEach-Object {
$user = $_
$alternativePhoneNumber = $user.StrongAuthenticationUserDetails.AlternativePhoneNumber
if($alternativePhoneNumber -eq $null) { 
$Result += New-Object PSObject -property @{ 
UserName = $user.DisplayName
UserPrincipalName = $user.UserPrincipalName
}
}
}
$Result | Select UserName,UserPrincipalName