Information Technology Reference
In-Depth Information
Key Point:
The configuration order of the call routing elements is: Devices, Route
Groups, Route Lists, Route Patterns. The call flow is the reverse: The dialed digits match a
Route Pattern, which points to a Route List, which points to a Route Group, which refer-
ences Devices.
Call-Routing Behavior
Digit analysis is the process by which CUCM matches dialed digits to possible targets for
call routing. Different protocols and devices perform digit analysis in different ways: Di-
aled digits are collected digit-by-digit on SCCP phones and SIP phones that use Keypad
Markup Language (KPML), and en-bloc (all at once as a set of digits) on basic SIP phones,
trunks, and most gateways.
Digit Analysis
The digit analysis logic that CUCM uses to select the target for the call-routing request is
based on the closest match. Consider the following set of Route Patterns:
1111
■
1211
■
1[23]XX
■
131
■
13[0-4]X
■
13!
■
With these Route Patterns in mind (these are not intended to be realistic; they just illus-
trate the pattern-matching logic), let's look at three examples of how CUCM will process
different dialed strings:
Example 1
If User A dials 1111, there is an exact match with the pattern “1111.” No
other patterns match, and the call is extended to that target.
Example 2
If User B dials 1211, CUCM has two possible matches:
1211:
Matches 1 digit string.
■
1[23]XX:
Matches 200 digit strings.
■
CUCM selects the closest match target (the one that matches the fewest possible strings)
(in this case, 1211).
Example 3
If User C dials 131, CUCM has four possible matches:
1[23]XX:
Matches 200 digit strings.
■
131:
Matches 1 digit string.
■
13[0-4]X:
Matches 50 digit strings.
■
13!:
Matches almost 10,000
quintillion
digit strings. (For our purposes, that is prac-
tically an unlimited number.)
■
