The European Union today threatened to regulate international roaming charges in its member countries, giving European carriers a six-month deadline to voluntarily mark down their prohibitively high roaming rates.

In a statement issued today, the European Commission “wants to ensure that prices paid by consumers for roaming services within the EU are not unjustifiably higher than those they pay for calling within their own country.” The Commission proposed a EU regulation that would effectively fix wholesale rates operators could charge other carriers to roam on their networks and retail rates those carriers could charge their customers, steps that European operators have resisted in the past. But the Commission tabled the regulation today to give carriers time to regulate themselves. The EU statement, however, said the EU-imposed rules could go into effect as soon as July 2007 if operators do not act and if the regulation is approved by the European Parliament and EU Council of Ministers.

The EU estimates that high roaming rates affect 147 million customers annually—110 million international business customers and 37 million tourists, which would make roaming an enormous revenue source for European carriers. While the EU is stepping up in Europe, there has been little movement to regulate roaming rates in the U.S. Many carriers already offer specially priced bundles for customers who travel to the U.S.’s closest neighbors, Canada and Mexico. As opposed to Europe, where borders are fairly fluid, the average U.S. customer doesn’t engage in too much international travel. Incompatible cellular technologies and spectral bands limit many customers calling ability, but in countries where roaming is possible U.S. carriers have initiated roaming agreements that range from $1 to $5 a minute, depending on the country.