Numbers in the whitelist are allowed to call in/called or both regardless of the Time Condition settings. The priority of whitelist is higher than blacklist.
You probably meet a problem that the number segments of your customers’ phone numbers happen to be listed in the blacklist. Don’t worry about it. Whitelist feature allows you to add dependable incoming/outgoing numbers which has higher priority than the blacklist, ensuring a seamless connection between you and your customers.