Bell code

Bell codes, buzzer codes or Communication Signal Appliance codes entail a series of bells or buzzers used on passenger trains for communication between the driver and guard.

All codes, except 3—2—1, must be acknowledged by repeating the code received.

In Japan, these are known as In-Car Communication Signals (Japanese: 車内連絡合図, romanized: Shanai renraku aizu). Each code must be acknowledged by the receiver. Examples of common railway bell codes are:

In the United States, these are known as Communication Signal Appliance codes.

• Whistle codes - used by locomotives to communicate with signal boxes