Using the electric utility to provide Internet access. Also called "power line communications" (PLC), high-frequencies carrying data are superimposed over the low-frequency waves on the electrical transmission lines. Modems plug into any electrical outlet in the home or office and connect to the computer. Deployed in Europe This technology has been successful in Europe, because a base station deployed at each 220-volt transformer serves up to 300 residences. Since 110-volt transformers in North America serve only a handful of customers, broadband over power lines has been slower to materialize. Somewhat Controversial There has been controversy over this technique because outdoor electrical lines are not shielded, and unshielded high-frequencies may interfere with other wireless signals in the atmosphere, including police and ambulance radio. See powerline network.