Glossary: H

A   B   C   D   E   F   G   H    I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z   Handset/ Headset Mode   Allows you to set the Handset (speakerphone on) mode or Headset (speakerphone off) mode. HFAB Hands Free Answer Back. Allows a speakerphone user to talk to an internal caller without lifting the handset. Also used to monitor a room. Hybrid A Hybrid key system can use single line telephones (SLT) in addition to an electronic proprietary telephone.