1. In the event of a dispute arising under this Directive between undertakings in different Member States, paragraphs 2, 3 and 4 of this Article shall apply. Those provisions shall not apply to disputes relating to radio spectrum coordination covered by Article 28.

2. Any party may refer the dispute to the national regulatory authority or authorities concerned. Where the dispute affects trade between Member States, the competent national regulatory authority or authorities shall notify the dispute to BEREC in order to bring about a consistent resolution of the dispute, in accordance with the objectives set out in Article 3.

3. Where such a notification has been made, BEREC shall issue an opinion inviting the national regulatory authority or authorities concerned to take specific action in order to resolve the dispute or to refrain from action, in the shortest possible time-frame, and in any case within four months except in exceptional circumstances.

4. The national regulatory authority or authorities concerned shall await BEREC's opinion before taking any action to resolve the dispute. In exceptional circumstances, where there is an urgent need to act, in order to safeguard competition or protect the interests of end-users, any of the competent national regulatory authorities may, either at the request of the parties or on its own initiative, adopt interim measures.