Roaming services provided by a mobile telephony provider established in a third country to its customers so that they can use the national mobile network of the Member State in which they are temporarily residing should, according to the CJEU, be considered to be subject to ‘actual use and operation’ within the territory of this Member State within the meaning of point (b) of Article 59a of the VAT Directive, which allows that Member State to designate the place of those roaming services as located in its territory where the exercise of such a right of option prevents those services remain tax-free within the Union, regardless of the tax treatment to which those services are subject in that third country.
Source BTW jurisprudentie
See also ECJ C-593/19 (SK Telecom) – Decision- Roaming services, effective use and enjoyment, VAT refund
