The configuration also includes a simple directory - this allows you to specify a simple mapping from calling numbers to names of callers for external calls (i.e. from carrier). The name is then filled in for the display name on the call.
The directory also allows for specific calling numbers to be marked as rejected or accepted for call screening. Ring groups and Telephone users can then have a screening control to reject calls based on this.
Numbers are matched for as many digits as you specify, and the first match found is used. If you match a shorter number then remaining digits are appended to the directory name specified.
Call screening does not apply to internal calls (i.e. from telephone users).