Hi Umesh,
The trigger param settings have been documented in the 2.5.1 Admin Guide itself. Please see the 'Managing Applications' portion of the guide for this, particularly the 'Understanding Scripts and Triggers' section for information on which trigger parameters may be used, and how they are to be defined.
Triggers can be defined in any of the following ways:
•

Single value—A trigger that activates when singe extension receives a call.
•

Value List —A trigger that activates when a call is received from more than one extension.
•

Single Regular Expression—A trigger that activates when a call is received on any of several extensions in a range.
•

Combined Method—A trigger that includes a single value trigger that activates when a single extension is called and a regular expression trigger that activates when a call is received from any of a range of extensions.
Note: 
A regular expression is indicated by adding regex: before the expression. You cannot mix literal values and regular expressions in a list. Only a single regular expression can be used as a trigger parameter for a given partition. The syntax [0-9] in a regular expression is equivalent to the Cisco Unified Communications Manager X notation used in route patterns and CTI Route point line numbers.
Also, please note that we currently have an issue with updation of trigger params. Please restart the appserver every time you update trigger params to work around this.
Thanks,
Neha