This feature allows individual trunks to be assigned to line keys on multiline telephone sets. The user can select a specific trunk for the purpose of originating a call or may answer an incoming call that appears on the appearance of that trunk. To originate a call, the user presses the appropriate line key and dials the desired number (no dial tone is returned). To answer an incoming call, the user presses the line key that has "ringing indication".
See Trunk Select - Direct for more information.