You have a Microsoft Teams Phone deployment that uses Teams Calling Plans, Direct Routing, and Operator Connect services. You need to enable PSTN services for 100 new users. The solution must minimize

Set-CsOnlineVoiceUser is a legacy cmdlet that is no longer the recommended method for number assignment and does not support Operator Connect numbers.

Set-CsUser can set some user telephony properties but is not the preferred or unified method for phone number assignment across all three PSTN service types.

Set-CsIPPhonePolicy configures settings for IP desk phones such as Teams-compatible hardware devices and has no role in PSTN number assignment.

Set-CsPhoneNumberAssignment replaces legacy number assignment methods and supports all PSTN connectivity types in a single cmdlet, allowing administrators to assign numbers to users regardless of whether the number comes from a Calling Plan, Direct Routing, or Operator Connect source, reducing the need for different workflows per service type.