This read-write value, 1 to 15, defines the digit this port outputs on the R2 signaling channel to indicate that the called destination is busy. It lets the port communicate busy status back through R2 in-band signaling to the originating exchange rather than the call simply timing out. For example, if the far-end exchange interprets digit 3 as a busy indication, this object must be configured to 3 so busy calls are reported correctly instead of being misread as another outcome.