According to the Commission's competition authorities, German mobile phone companies Vodafone and T-Mobile are overcharging customers of foreign operators when they make mobile calls when visiting Germany.
The Commission has therefore started an investigation into these 'roaming' prices. If found guilty, both companies could be fined up to 10% of their annual turnover.
The Commission started a similar case against UK operators Vodafone and O2 in July 2004.
'Roaming' is the facility that mobile phone subscribers have to use their phones while travelling abroad.
