The arrival of Advanced 800 Service meant that numbers originally limited for use in Canada became available to American customers, and vice versa. Originally, 800-services were isolated between the US and Canada, but in 1984, an agreement between carriers in the two countries allowed the numbers in each country to be accessible to the other providers of 800 service were able to add zones to cover the expanded areas able to be offered. Open competition also brought an end to the pattern of long distance subsidizing local service, bringing per-minute charges down to levels where any business could afford to take orders using an 800-number. The toll-free long distance market was opened to competition after 1986 and a RespOrg system instituted in 1993 to provide toll-free number portability between rival carriers using the SMS/800 database. By breaking the link between the number's exchange prefix and geographic location, this system opened opportunities for vanity number advertising – an advantage in media like commercial radio where numbers need to be memorable. In the early 1980s, Bell Labs received a patent for what became AT&T's 'Advanced 800 Service', a computer-controlled system where any toll-free number could point to any destination number, such as to a small business local number instead of a special InWATS line, and an itemized bill generated only for the calls the business actually received. Typically, a service provider offered a variety of zones, each costing more than the smaller ones, but adding progressively larger areas from which calls would be accepted for a customer. The billing of calls was not itemized and the expensive fixed-rate line was only within financial reach of large corporations and government agencies. These terminated on special fixed-rate trunks which would accept calls from a specified calling area with either no limit or a specific maximum number of hours per month. The first automated toll-free numbers were assigned with area code 800, created as inbound Wide Area Telephone Service (InWATS) in 1966 (U.S.

Initially, all of these calls had to be completed by the switchboard operator. Some businesses, eager to sell their products to buyers outside the local calling area, were willing to accept collect calls or installed special services, such as Zenith number service, where they paid the cost of receiving telephone enquiries. As regulators in North America had long allowed long-distance calling to be priced artificially high in return for artificially low rates for local service, subscribers tended to make toll calls rarely and to keep them deliberately brief. Most of the United States and all of Canada uses a flat-rate structure for local calls, which incur no per-call cost to residential subscribers. 3 Assignment of NANP toll-free telephone numbers.

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