10-10-321 is a Unite States long-distance phone service best known for its prolific television and Direct Mail advertising in the late 1990s. 10-10-321 was the first mass-marketed service of its type, and it and the similar 10-10-220 and 10-10-900 services were all owned by Telecom USA, which was owned by MCI. All services of its kind essentially allow consumers to bypass, or "dial-around" their primary long-distance carrier and use a different one.