The secrecy button mutes sound for the person on the phone, so you can converse without them overhearing. The Logik L04CTAM10 is also switchboard compatible.
LOGIK L05CBIG10 Corded Big Button Phone Loud Ring Telephone Red Indicator Light
LOGIK L05CBIG10 Corded Big Button Telephone with Speakerphone - Complete Set
Logik L05CBIG10 Corded Desk Telephone Big Button Speakerphone White
LOGIK L05CBIG10 Corded Big Button Telephone with Speakerphone
