To count skype for business users

To count skype for business users in a Pool

PS C:\Users\admin> (Get-CsUser -Filter {RegistrarPool -ne "SFBPool.mydomain.com"}).count

2140

To count skype for business online users

PS C:\Users\admin> (Get-CsUser -Filter {hostingprovider -eq "sipfed.online.lync.com"}).count

2140

To count skype for business users

PS C:\Users\admin> (Get-CsUser).count

3633

Search or filter users on the basis of mobile attribute in Active directory

 PS C:\Users\adsync> $var="123456789"

PS C:\Users\adsync> Get-ADUser -Filter {mobile -like $var} -Properties name |select name