CUCM <None> CSS and PT

From an old CUCM Sytem Guide:

"Before you configure any partitions or calling search spaces, all directory numbers (DN) reside in a special partition named <None>, and all devices are assigned a calling search space also named <None>. When you create custom partitions and calling search spaces, any calling search space that you create also contains the <None> partition, while the <None> calling search space contains only the <None> partition."

Short story:

• <None> partition is accessible from everywhere.
• <None> calling search space can only access the <None> partition.