Feature Server (FS)

Implements Call Forward, Call Screening, Call Blocking
- The “Core Features” are implemented “within the network”
  - for example, you can’t implement features in a phone which is not there!
  - you cannot give an end system the caller’s ID, but guarantee that they do not display it, …
Execute arbitrary Call Processing Language (CPL) scripts written by users
- CPL is parsed into eXtensible Markup Language (XML) document object model (DOM) trees, these are then turned into state machines (in C++), then executed.

[slide524] They supported CPL.