This will list all used phone numbers in Lync. Except those used by Exchange UM (Auto Attendant ..)

$LUser=Get-csuser -Filter {LineURI -ne $Null}
$PLUser=Get-CsUser -Filter {PrivateLine -ne $Null}
$LCommonarea=Get-cscommonareaphone -Filter {LineURI -ne $Null}
$LAnaloge=Get-csanalogdevice -Filter {LineURI -ne $Null}
$LAppEndPoint=Get-CSApplicationEndPoint -Filter {LineURI -ne $Null}
$LExchUM=Get-CsExUmContact -Filter {LineURI -ne $Null}
$LDialIN=Get-CsDialInConferencingAccessNumber -Filter {LineURI -ne $Null}
$Workflow=Get-CsRgsWorkflow
$LDevices=$LDialIN+$PLUser+$LUser+$LCommonarea+$LAnaloge+$LAppEndPoint
$LDevices|sort-object -property Lineuri | ft DisplayName,LineUri