CUCM Calling Search Spaces and Partitions: Explained with Star Wars

About this video

A tutorial on Cisco Unified Communications Manager (CUCM) class of control, explained through a Star Wars dial-plan design. Partitions are containers grouping dialable destinations — directory numbers, route patterns, translation patterns, voicemail ports — answering ‘who can call me.’ Calling Search Spaces (CSS) are groups of partitions assigned to devices or lines, answering ‘who can I call.’ By default everything sits in the null/none partition and null CSS, where everyone can dial everyone, which he warns is insecure. In the example, the Death Star partition holds internal numbers, Tatooine represents local outbound route patterns, and a distant outer-rim planet represents international dialing. Stormtroopers (basic users) get only the Death Star partition; Captains (managers) get Death Star plus Tatooine; Darth Vader and the Emperor get everything. To stop stormtroopers dialing the executives despite sharing the Death Star partition, he creates a blocking translation pattern in a separate partition, puts it in a ‘force-choked’ CSS, and assigns that CSS to the line — line CSS takes priority and concatenates with the device CSS. He shows the inverse design too (one permissive Empire CSS on all phones, restrictions only via line CSS block partitions), stresses that being in the same partition does not let you dial someone — your CSS decides — illustrated by a contractor who can only dial international, and walks through creating partitions and CSSs under Call Routing > Class of Control in CUCM Administration.

Key takeaways

• Partitions group dialable destinations; a Calling Search Space groups partitions and is assigned to a phone or line to control what it can dial
• The default null/none partition has zero restrictions — everything should be moved out of it for any security
• Tier access with partitions/CSS: basic users internal only, managers internal plus local outbound, executives internal plus local plus international
• Blocking is done with translation patterns set to block in a dedicated partition, placed in a line CSS which overrides/concatenates with the device CSS
• Membership in the same partition does not grant calling rights — the caller’s CSS alone determines reachable partitions

Episode details: published January 24, 2017 · 17:16 long. Summary written by Self Growth Videos from the episode itself. Business results and any income figures mentioned are NetworkChuck’s own claims, shared for education — they are not typical or guaranteed.

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