Count how many users in OCS and Lync

OCS:

(Get-CsUser -OnOfficeCommunicationServer).Count 

Lync:

(Get-CsUser -OnLyncServer).Count

                 (or)

Get-CsUser -OnLyncServer | Measure

Counting Enterprise Voice Enabled Users in Lync:

(Get-CsUser -OnLyncServer -Filter {EnterpriseVoiceEnabled -eq $true}).count

Total number of Lync Enabled Users:

Get-CsUser -Filter {Enabled -eq $true} | Measure

Count the number of users pointing to the Lync Registrar Pool:

Get-CsUser | Where-Object {$_.RegistrarPool -match "Lync Pool FQDN"} | Measure