576-25-700 DBS 576 (USA), issued March 1999 19Chapter 3. System FeaturesSystem Features are either available on a system-wide basis or aid in the overall administration of theSystem.This chapter contains detailed descriptions of the following System Features:Topic PageAEC Disconnect 22Attendant Groups 22Automatic Call Distributor 23Automatic Route Selection 24Automatic Trunk to Trunk Transfer 25Background Music/MOH Separation 25Battery Backup 26Building Block Expansion Capability 26Built-In Voice Mail Unit 27Call Progress Tones 27Caller ID 28Caller ID Alpha Tagging (Not Available in USA) 29Centrex/PBX Compatibility 29Class of Service 30Class of Service - Trunk/Tie 30Class of Service - Ext/Ext Restriction 31Class of Service - Extension Feature 31Class of Service - Trunk to Trunk Restriction 33Class of Service - Extension (Station) Timers 33CO Ringing Types 34DID Ringing 34DIL Ringing 35DISA Ringing 35Multiple Ringing 36CO Trunk Interface 36CO Trunk Interface - DID 36CO Trunk Interface - Ground Start 37CO Trunk Interface - ISDN BRI 37CO Trunk Interface - ISDN-PRI 37CO Trunk Interface - Loop Start 38Computer Telephony Integration Capability (USA Only) 38Data Security 39