1.13.4 Music on Hold ...............................................................................................................1731.14 Conference Features ....................................................................................................1761.14.1 Conference Features ....................................................................................................1761.14.1.1 Conference Features—SUMMARY ...........................................................................1761.14.1.2 Conference ................................................................................................................1771.14.1.3 Privacy Release .........................................................................................................1791.15 Conference Group Call Features .................................................................................1801.15.1 Conference Group Call .................................................................................................1801.16 Paging Features ............................................................................................................1831.16.1 Paging ..........................................................................................................................1831.17 Optional Device Features .............................................................................................1861.17.1 Doorphone Call ............................................................................................................1861.17.2 Door Open ....................................................................................................................1881.17.3 Trunk Answer From Any Station (TAFAS) ...................................................................1891.17.4 Background Music (BGM) ............................................................................................1901.17.5 Outgoing Message (OGM) ...........................................................................................1921.17.6 Direct Inward System Access (DISA) ...........................................................................1951.17.7 Built-in Simplified Voice Message (SVM) .....................................................................2041.17.8 External Sensor ............................................................................................................2111.17.9 External Relay Control .................................................................................................2131.18 Caller ID Features ..........................................................................................................2141.18.1 Caller ID .......................................................................................................................2141.18.2 Incoming Call Log .........................................................................................................2191.19 Message Features .........................................................................................................2211.19.1 Message Waiting ..........................................................................................................2211.19.2 Absent Message ...........................................................................................................2251.20 Proprietary Telephone (PT) Features ..........................................................................2271.20.1 Fixed Buttons ...............................................................................................................2271.20.2 Flexible Buttons ............................................................................................................2301.20.3 LED Indication ..............................................................................................................2331.20.4 Display Information .......................................................................................................2361.21 Integrated Services Digital Network (ISDN) Service Features ..................................2381.21.1 Integrated Services Digital Network (ISDN) .................................................................2381.21.1.1 Integrated Services Digital Network (ISDN)—SUMMARY ........................................2381.21.1.2 Calling/Connected Line Identification Presentation (CLIP/COLP) .............................2431.21.1.3 Advice of Charge (AOC) ............................................................................................2461.21.1.4 Call Forwarding (CF)—by ISDN (P-MP) ....................................................................2471.21.1.5 Call Forwarding (CF)—by ISDN (P-P) .......................................................................2491.21.1.6 Call Hold (HOLD)—by ISDN ......................................................................................2511.21.1.7 Call Transfer (CT)—by ISDN .....................................................................................2521.21.1.8 Three-party Conference (3PTY)—by ISDN ...............................................................2531.21.1.9 Malicious Call Identification (MCID) ...........................................................................2541.21.1.10 Completion of Calls to Busy Subscriber (CCBS) .......................................................2551.21.1.11 ISDN Extension .........................................................................................................2561.21.1.12 ISDN Service Access by Keypad Protocol ................................................................2581.22 E1 Line Service Features ..............................................................................................2591.22.1 E1 Line Service ............................................................................................................2591.23 T1 Line Service Features ..............................................................................................2611.23.1 T1 Line Service ............................................................................................................2611.24 Voice Mail Features .......................................................................................................2631.24.1 Voice Mail (VM) Group .................................................................................................2631.24.2 Voice Mail DTMF Integration ........................................................................................2661.24.3 Voice Mail DPT (Digital) Integration .............................................................................2731.25 Portable Station (PS) Features ....................................................................................2781.25.1 Portable Station (PS) Connection ................................................................................27810 Feature GuideTable of Contents