Indicators and Display
| Circuit / Schematic diagram | Description |
|
Telephone line indicator (circuit on demand) |
Indicated the status of telephone connected to a common line. |
| Telephone on/off hook indicator | The circuit gives audio/visual indication of on/off hook and ringing modes. |
| Telephone in use indicator | It will allow users to know if the phone is being used and not to pick up the phone. |
| Extension free indicator | Indicates if another phone using the same line is free or not. |
| Telephone busy indicator | Indicates if any telephone in the same line is busy or not |
| Caller Identification | |
| Caller Identification 2 | |
| Caller Identification 3 | |
| Telephone Billing machine | Circuit can be used in PCO for displaying the actual call time. |
| Telephone call meter using calculator | Displays the call time and based on simple calculator and COB |
| Smart Phone light | The circuit shown here is used to switch on a lamp when the tele- phone rings |
| Talking phone dial monitor | Detects the number pressed and speaks the dialed number |
| Telephone dial alarm | Microcontroller based. |
| Telephone number display | The given circuit, when connected in parallel to a telephone, displays the number dialled from the telephone set using the DTMF mode. |
| DTMF Tone Decoder | Displays telephone numbers decoded from tones |