1. Field of the Invention
The present invention relates to a self-contained signaling and control device for detecting telephone dual-tone multi-frequency (DTMF) tones and generating a signal upon detection of a DTMF tones sequence that matches a preset sequence as a code. The signal may be, for example, an audible signal, a visual signal or a control signal to drive an auxiliary device.
2. Description of Related Art
Homes, offices and other places often have several telephones which are connected in different locations to a single telephone line. Where a private telephone exchange is not involved, there is the problem of "call transfer." For example, a first user who picks up the phone to receive a call and wants to "transfer" the call to a second user must, e.g., shout to the second user or go to the location of the second user to tell the second user to pick up the phone.
To address this situation, there are a variety of known signaling devices designed to signal from one telephone location to another. For example, there are private telephone exchanges that have signaling as well as many additional features. There are also other devices which differ from each other by various features, such as the intended use thereof or the operating method and components. However, these devices require an external current supply to operate, necessitating a power source such as a battery.