Cisco CallManager Partition and Calling Search Spaces (CSS) Explained

Cisco CallManager partitions and calling search spaces (CSS) are confusing. This Tech-Recipe describes how I keep track of how they work.


Partitions contain items such as phones, gateways, and route patterns.

CSS show which things can see other things.

Note the following examples:

Phone1 is in partition Phone1-P.
Route Pattern 911 is in partition Site1-911-P
Route Pattern 9.! is in partition Site1-Unrestricted-P.

CSS Site1-911 contains the Site1-911-P and Phone1-P partitions.
CSS Site1-UR contains the Site1-911-P, Phone1-P, and Site1-Unrestricted-P partitions.

When the Site1-911 CSS is applied to a directory number (DN), the dialed digits “911″ match the 911 route pattern, and the call is routed to the pattern’s gateway Gateway1. Other dialed digits will not match any patterns, since the 9.! pattern is not in this CSS, and the call ends.

When the Site1-UR CSS is applied, the DN can dial any digits and find a match via the 9.! pattern.

NOTE: “!” is a pattern that matches all digits, regardless of length.

The Conversation

Follow the reactions below and share your own thoughts.

  • prajith

    How to call between two DNs of two different Calling Search Space in a single CUCM

  • david franco

    brief and to the point – thanks

  • RsR

    excellent.