what is a Speakerphone???

A speakerphone is a telephone with a microphone and loudspeaker provided separately from those in the handset.

Many telephones have an integrated speakerphone function which can be activated by pushing a single button. This button transfers the sound input and output from the handset to the ambient microphone and loudspeaker. Devices designed specifically for speakerphone use often have multiple microphone inputs arranged radially around the device to maximize sound input, such as may occur around a conference table. The most sophisticated units allow the connection of additional satellite microphones that can be placed some distance from the main unit.

 This device allows multiple persons to participate in a conversation. The loudspeaker broadcasts the voice or voices of those on the other end of the telephone line, while the microphone captures all voices of those using the speakerphone.