One other way to get the MUTE feature installed, and be able to have it cancel automatically, is to use the contacts provided on the extra switch hook contacts along with the white "pull up" switch hook plunger. When it's pulled up, it mutes, and it automatically resets when the handset is hung up. There are enough contacts to activate the lamp under the HOLD button for that, too.

Getting the 107A to monitor the phone is possible. Getting the ability to dial while on-hook, without a lot of relays, will be difficult. The speakerphone units, both 3-type and 4-type, rely on extra switch hook contacts and control wires to accomplish that.


Arthur P. Bloom
"30 years of faithful service...15 years on hold"