Call Routing in Cisco’s Unified Call Manager (CUCM)

The most fundamental component of a unified communications system is the cal routing database used to perform digit analysis and direct traffic to the intended destination.  This document servers as a reminder of how that database works with the Cisco Unified Call Manager (CUCM)

CUCM call routing use the following components:

  • Route Pattern (RP)
  • Route List (RL)
  • Route Group (RG)
  • Gateway/Trunk (GW/ICT)

When calling, Cisco phones use Skinny (SCCP) to send their digits to the CUCM where the routing DB is used to make direct the call.  Once analysis is complete the call will be routed to the called party.

Routing Patterns make use of wild cards, but it should be noted that the more specific the pattern the higher preference given to that particular entry.  These are fairly similar to Unix wildcards.  Entries can look like this:

  • 1208 – An exact number match used for directory numbers that are assigned to a partition and route to a specific Cisco IP phone (SEP001894AAAAAA)
  • 120X – 1200 to 1209 plus 120* and 120#
  • 120[5-9] – 1205 to 1209. Translation patterns used to route unassigned calls to the operator.
  • 120[^0-4] – 1205 to 1209 (exclude 0-4).  I don’t think we use these.
  • . – Digit stripping and manipulation
  • 9.@ – Route pattern used at most companies for outgoing calls where you dial 9
  • # – timing out for International calls

In the CUCM 5 take a look at “Call Routing | Route Plan Report” and you will see your current  plan.  They are listed in 5 columns. The first is a graphic representation of  the 4th (Type).  The others are Pattern, Partition and Route Detail.

This is from a conversation with a friend and some reading I did some time ago.   Thanks JM for teaching me.