info ADT

Status Chime mode (3 beeps)

Indicates the CHIME function is active; alerts user when perimeter zone is open.

? What Causes This

Enabled chime feature on system disarmed status.

What This Means

Ensure only intended areas are open during chime mode activation.

Source: page 23 of the official manual

From the manual

Manual page 23 — ADT error Chime mode (3 beeps)

This error code appears in:

ADT Safewatch Pro 3000