The decision concerns the so- called mobile termination rates (MTRs), which is the fee one operator charges the other for a call made to the other's network. For years Mobistar and Base have been allowed to charge higher rates than Belgacom, the other main operator on the national mobile scene. That leeway was allowed them on their entry to the market, in order to offset the massive advantage Belgacom had as the existing state monopoly.

The BIPT called in August for the MTRs to be cut by almost one-half, to 4.92 euro cents for Mobistar (from 9.02) cents, and to 5.68 euro cents for BASE (from 11.43 cents). Belgacom's MTR is currently 4.52 cents. All differences between the operators will disappear in 2013.

Mobistar later said its profits would fall and its dividend be cut as a result of the decision. The company also said it would consider appealing against the decision.