Shows where calls to a time condition go, without changing anything.

• At given times: pass times to see which route each call would take.
• Over a period: pass from and to to get every stretch where the routing stays the same.
• Before you save a change: add the conditions (and optionally closed_action) you're about to save. Each result then shows the live route beside the proposed one, and range.changed_windows lists exactly when your change would route calls differently. An empty list means the change makes no difference in that period.

The simulation reads the schedule exactly as the phone system runs it, including its time zone. Dated entries (holidays, closures) use the phone system's local time; weekly hours use the time zone calls to this schedule carry (the account's setting, one for this schedule alone, or the phone system's default). time_zones says which zones were used.

A schedule that routes calls by the caller's number needs caller_number.

It never guesses: if the schedule, the proposal or the account's time zone uses something it can't evaluate with certainty, or a time is outside 1970 to 2037, the response is 422 with the reasons instead of a result.