Toll-free numbers are formatted and dialed the same way as eleven digit domestic long-distance calls, where the area code is one of 800, 866, 877 or 888. Domestic long distance calls are placed as 1-NPA-NXX-XXXX, where the 1 means long distance, NPA is the area code, NXX is the office code and XXXX is the subscriber. To give an example, Cisco's toll-free number for TAC is 1-800-553-2447.
If you are interested in more information on the North American Numbering Plan, you can get more information at the NANPA website at http://www.nanpa.com. You can also look at the NANP file in C:\Program Files\Cisco\DialPlan on a CallManager, which shows more detail on how CallManager handles the @ token and route filters, and restrictions on what area codes and office codes are considered valid.
