Calling Plans do not require a Voice Routing Policy, but an additional license:

 Calling Plans do not require a Voice Routing Policy, but an additional license: Set-AzureADUserLicense - Used to apply PhoneSystem and Calling Plan license Set-CsOnlineVoiceUser - Used to apply Microsoft Phone Number to the User Set-CSUser - Enables the User for EnterpriseVoice

Grant-CsOnlineVoiceRoutingPolicy is for direct routing,