Handbook:Advanced Server Configuration:Time-of-Day Usage Scheduling
HylaFAX can be configured so that outbound calls are placed only during certain hours of the day. This can optionally be configured on a per-destination basis, making it easy to reduce phone costs by processing toll calls only during the time when off-peak rates are available.
By default outbound calls are permitted at any time. To constrain calls to a particular time or range of times the TimeOfDay parameter can be setup according to the syntax specified in hylafax-config(4F). This syntax is consistent with the syntax used by the UUCP software. For example, to permit outbound calls only between 9AM and 5PM local time the following might be used:
TimeOfDay: "0900-1700"