Comdial DXP, DXP Plus, FX Attendant Manual page 150

Speakerphone Characteristics
• In some situations, such as when either you or the distant party
are in a noisy environment, you may have to lift your handset to
ensure a clear conversation.
• When both you and the distant party use speakerphones, the
sound-activated switches can occasionally detect both voices
simultaneously, thus blocking out both voices.
140 Comdial August, 03