Call Processing Language (CPL) is a language that can be used to describe and control Internet telephony services. It is designed to be implementable on either network servers or user agent servers. It is meant to be simple, extensible, easily edited by graphical clients, and independent of operating system or signaling protocol. It is suitable for running on a server where users may not be allowed to execute arbitrary programs, as it has no variables, loops, or ability to run external programs.
In Case of Session Initiation Protocol Servers(SIP servers),it can be used to specify the user defined preferences like (please refer to the rfc3880 for further details)
1)Authenticate calls To And From The user
based on
Address Info -callerid
-domain of caller
-domain of callee
-display name of caller/callee
DateTime of call
-day of call
-hour of call
-minute of call
-year of call
language preferences
priority over subscribed numbers
2) modification of user locations in server through UI
3) Call routing logic
-how long to ring a phone
before doing further action
based on the result of the call
like --busy
--noanswer
--notfound
and then take appropriate
action
etc.... etc...