Intelligent multimode message alerts

Interrupted tone converter

Intrinsically safe telephone

ISDN interface unit with separate ring generator

Light controlled telephone ringer

Light emitting diode message waiting lamp circuit

Line circuit for driving a ringer and a service indicating lamp

Line-powered detection of call progress tones

Message and ringing signaling device for a telephone installatio

Method and apparatus enabling a calling telephone handset to...

Method and apparatus for controlling the ring volume of a teleph

Method and apparatus for customizing an audio file in a...

Method and apparatus for implementing a bandlimited ringing...

Method and apparatus for processing an incoming telephone call s

Method and apparatus for producing ringing tones in a...

Method and apparatus for providing customized ringbacks

Method and apparatus for selecting an alert mode based on...

Method and circuit for detecting ring and caller-ID signals

Method and system for audibly announcing an indication of an...

Method and system for called party to provide indication...