According to Article 2 (Definitions) of Regulation (EU) 2017/373:
‘Pan-European service’ means an activity which is designed and established for users within most or all Member States and which may also extend beyond the airspace of the territory to which the Treaty applies.
The competent authority with regard to Pan-European services (e.g. DAT providers, the Network Manager, etc.) shall be the Agency (EASA) as defined in Article 4(1) of Regulation (EU) 2017/373.