Active dipole telephone line protection device
Apparatus for converting a standard telephone to an unlisted num
Apparatus for restricting telephone calls
Automated personalized telephone management system
Automatic positive telephone disconnect system
Call screening device
Call screening in a public telephone station
Caller discrimination within a telephone system
Calling party identifying apparatus and method therefor
Coded phone security system
Communication support system for providing security of...
Communication support system for providing security of...
Communication terminal unit for connection to an ISDN
Controllable annunciator using ring signal
Dial tone interrupt device
Dual-line telephone bridging device that gives remote telephones
Intelligent multifunction device for analog telephone subscriber
Lockout apparatus for controlling communications on a single...
Lockout telephone
Method and apparatus for controlling telephone line access