Welcome to the World Tone Database, dedicated to the A-Z of international call progress tones. From here you can research tone parameters in national tone plans and hear the tones on-line.
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| Country | Tone | Frequency/Hz | Cadence/s | Audio |
| Bulgaria | Busy tone - I | 425 | 0.5 on 0.5 off |  |
| Bulgaria | Busy tone - II | 425 | 0.2 on 0.5 off | |
| Bulgaria | Busy tone - III | 425 | 0.25 on 0.25 off | |
| Bulgaria | Busy tone - IV | |||
| Bulgaria | Call waiting tone - I | |||
| Bulgaria | Call waiting tone - II | |||
| Bulgaria | Call waiting tone - III | |||
| Bulgaria | Congestion tone - I | |||
| Bulgaria | Congestion tone - II | |||
| Bulgaria | Congestion tone - III | |||
| Bulgaria | Dial tone - I | |||
| Bulgaria | Dial tone - II | |||
| Bulgaria | Dial tone - III | |||
| Bulgaria | Dial tone - IV | |||
| Bulgaria | Disconnect tone | |||
| Bulgaria | Disconnect tone | |||
| Bulgaria | Holding tone - I | |||
| Bulgaria | Holding tone - II | |||
| Bulgaria | Intrusion tone - I | |||
| Bulgaria | Intrusion tone - II | |||
| Bulgaria | Intrusion tone - III | |||
| Bulgaria | Payphone recognition tone | |||
| Bulgaria | Ringing tone - I | |||
| Bulgaria | Ringing tone - II | |||
| Bulgaria | Ringing tone - III | |||
| Bulgaria | Special dial tone | |||
| Bulgaria | Special information tone | |||
| Bulgaria | Warning tone - I | |||
| Bulgaria | Warning tone - II | |||
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