It is possible that the discount time periods for local calls are different from those for across-country calls, which may also be different from those for overseas calls. You can make the fax scheduler aware of this by setting up the different tariffs for the three types of calls. See Creating a New Tariff to find out how you can do that.
Next, you set up three different dialing rules for the three type of calls. For local calls, the dial string might simply be a 7-digit number. You then select using "Trunk Group 1" the one type of line you have. For "Tariff 1", you select the local call tariff that you have created above.
Likewise, you create a dialing rule for the across-country calls. The dial string will need to include 1 or the access code of your long distance carrier plus the area code. Similarly, you then select using "Trunk Group 1" the one type of line you have. For "Tariff 1", you select the across-country call tariff that you have created above. If you have access to other long distance carriers or leased lines by dialing different access codes, you should put them into this dialing rule as well. Create tariffs for them and use "Tariff 2" and so on.
You can follow the same procedure to create a dialing rule for the overseas calls except that the dial string will need to include the overseas access code plus the country code, and you select the overseas call tariff instead.
This way, different types of calls will be scheduled by the fax scheduler using the corresponding tariff rate schedule if the fax you are sending is using a class that has a long deadline in order to let the fax scheduler determine the cheapest time to transmit the fax.