Ten-digit dialing

In seven-digit dialing the area code is dialed only when the area code of the called number is different from that of the calling number. Some communities on an area code boundary, such as Ottawa-Hull (613/819), Kansas City MO/KS (816/913) or Washington, D.C. (202) implemented central office code protection to ensure the same seven-digit local number was not assigned in two different area codes in the same city to retain seven-digit dialing in the entire community. Code protection is not possible for calls across area code boundaries within split plan cities where area codes have been added due to a shortage of available local numbers; these local calls became ten digits when the code was split.

Question: do you always have to dial an area code
Answer: no