Three South Dakota companies that provide local telephone access and other services are suing three long-distance companies that have countersued over a practice known as traffic pumping.

The local exchange carriers say the long-distance providers aren't paying their bills - more than $13 million.

The national companies that pay the local carriers accuse them of driving up costs by flooding lines with teleconference calls and other services.

The three South Dakota plaintiffs include Sancom Inc. of Mitchell, Northern Valley Communications LLC of Aberdeen and Splitrock Properties Inc. of Garretson.

The defendants include AT&T Inc., Sprint Communications Co. LP, Verizon Business Services and Qwest Communications International Inc.

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