1601-02: DIL No Answer Timer [System: > Timers: > Features: > Incoming (1601):

Use this option to set how long a DIL to an extension rings an idle extension before Key Ring or overflow occurs.

This option also sets how long a call rings the overflow destination before diverting to Key Ring. Key Ring rings all extensions programmed to ring for that line.
This timer also sets the interval after which DID Line Overflow and DID Station Intercept occur.

1601-02: DIL No Answer Timer [System: Timers: Features: Incoming (1601): DIL No Answer]