Ringing signals to operators are obsolete due to automation. Ringdown circuits are used in various settings, connecting phones directly. They are used in businesses and emergency services, providing a fast connection without dialing. They are also useful in stock trading for instant connection.
A ringer sends a signal to a telephone operator or activates an automatic circuit when a telephone is activated. In a system for contacting operators, ringing is largely obsolete, as automation has replaced many operator functions and it is no longer necessary to use an operator to place a call in many environments. Circuits that work with a similar signaling method, where going off-hook a phone completes a connection, are used in a variety of applications.
The original example of ringdown was seen in connections where the user had to signal an operator to use the phone. When someone picked up a phone, he sent a signal current to a phone company technician, who could place a call at the user’s request. When the call ended, people would have to “call back,” telling the operator they were done and hanging up the phone to break the connection. This technology is no longer in widespread use.
Similar circuits where a ringdown communicates directly with a circuit, not an operator, can be seen in a variety of settings. In such systems, when someone picks up a phone, the circuit is activated and another phone rings. Multiple units can be connected to the circuit to allow a single caller to ring multiple phones simultaneously for conferencing. In fact, a dedicated line is created, with a direct connection between the two or more telephones.
An example of a ringdown circuit can be seen with courtesy telephones installed in businesses. People anywhere in the store can pick up one of these phones to be connected to a salesperson who can assist them. Such connections are also used by emergency services, courtesy taxis and so on. An advantage of such systems is that people do not need to know and dial a number to connect, since only picking up the phone switches to the call.
In addition to being used as a courtesy and public safety measure, calling circuits can also be useful in situations where people frequently dial numbers and want a fast connection. A classic example can come in stock trading, where entry-level traders may have phones at their desks that connect instantly to an office, information line, or other resource. You can waste valuable time dialing and waiting for a call, while the ringtone allows for instant connection.
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