In general, there are two types of doorbell chime.
Digital chime: plays a recording, which may have any number of tones.
Mechanical chime: activates an electromagnet to move a striker that hits a metal bar within the chime box. There are usually only 2 or 3 sounds from a mechanical chime, limiting the variety it can make.
The Blink Video Doorbell is compatible with the power spec. of a mechanical chime in North America: 16 - 24 Volts AC, at 50 - 60 Hz, and 40 Volt Amperes maximum.
If your chime system has less than 16 VAC, it can still ring when the doorbell is pressed, but your system enters Event Response and you are not able to start actions from the Blink app, like open a Live View session or take a thumbnail. To add these features, connect the doorbell to a Sync Module system.
Wiring for external doorbell buttons often has significant corrosion that can prevent enough current from being available. Be sure to connect only bare wires to the doorbell terminal posts, and remove corrosion if present.
When you discover your chime type, click a link below to visit its calibration article.