2.5.4.5 Reverse Circuit ..........................................................................................................1012.5.4.6 Trunk Busy Out ..........................................................................................................1022.5.4.7 Pause Insertion ..........................................................................................................1032.5.4.8 Host PBX Access Code (Access Code to the Telephone Company from a HostPBX) ..........................................................................................................................1042.5.4.9 Special Carrier Access Code .....................................................................................1062.5.5 Seizing a Line Features ................................................................................................1072.5.5.1 Seizing a Line Features—SUMMARY .......................................................................1072.5.5.2 Line Preference—Outgoing .......................................................................................1082.5.5.3 Trunk Access .............................................................................................................1092.6 Memory Dialling Features ............................................................................................1112.6.1 Memory Dialling Features—SUMMARY ......................................................................1112.6.2 One-touch Dialling ........................................................................................................1132.6.3 Last Number Redial ......................................................................................................1142.6.4 Speed Dialling—Personal/System ...............................................................................1162.6.5 Quick Dialling ...............................................................................................................1182.6.6 Hot Line ........................................................................................................................1192.7 Toll Restriction (TRS)/Call Barring (Barring) Features ..............................................1202.7.1 Toll Restriction (TRS)/Call Barring (Barring) ................................................................1202.7.2 Budget Management ....................................................................................................1272.7.3 Extension Dial Lock ......................................................................................................1282.7.4 Dial Tone Transfer ........................................................................................................1292.7.5 Walking COS ................................................................................................................1302.7.6 Verification Code Entry .................................................................................................1322.8 Automatic Route Selection (ARS) Features ...............................................................1342.8.1 Automatic Route Selection (ARS) ................................................................................1342.9 Primary Directory Number (PDN)/Secondary Directory Number (SDN)Features .........................................................................................................................1402.9.1 Primary Directory Number (PDN)/Secondary Directory Number (SDN)Extension ......................................................................................................................1402.10 Busy Line/Busy Party Features ...................................................................................1462.10.1 Automatic Callback Busy (Camp-on) ...........................................................................1462.10.2 Executive Busy Override ..............................................................................................1472.10.3 Call Monitor ..................................................................................................................1492.10.4 Second Call Notification to Busy Extension .................................................................1512.10.4.1 Second Call Notification to Busy Extension—SUMMARY .........................................1512.10.4.2 Call Waiting Tone ......................................................................................................1532.10.4.3 Off-hook Call Announcement (OHCA) .......................................................................1542.10.4.4 Whisper OHCA ..........................................................................................................1552.11 Conversation Features .................................................................................................1572.11.1 Hands-free Operation ...................................................................................................1572.11.2 Off-hook Monitor ...........................................................................................................1582.11.3 Mute .............................................................................................................................1592.11.4 Headset Operation .......................................................................................................1602.11.5 Data Line Security ........................................................................................................1612.11.6 Flash/Recall/Terminate ................................................................................................1622.11.7 External Feature Access (EFA) ....................................................................................1632.11.8 Trunk Call Limitation .....................................................................................................1642.11.9 Calling Party Control (CPC) Signal Detection ..............................................................1662.11.10 One-numbered Extension ............................................................................................1672.12 Transferring Features ...................................................................................................1692.12.1 Call Transfer .................................................................................................................1692.12.2 SIP Refer Transfer .......................................................................................................1732.13 Holding Features ...........................................................................................................1742.13.1 Call Hold .......................................................................................................................1748 Feature GuideTable of Contents