This article examines the legal scope of communication privacy in the telecommunication services and territorial application in Japan and the EU. Both face similar regulatory challenges regarding how to ensure a level playing field between incumbent services and emerging ones, and how to protect communication privacy in Over-The-Top (OTT) services. A difference between Japan’s and the EU’s current legislation is that Japan’s regulatory framework has the issue of extraterritorial application, whereas the issue in the EU is the scope of regulatory services and territory. The EU has proposed a revision of law to address the issue, whereas Japan has not taken any measures, despite an increase in the number of people using OTT services and accompanying demand for ensuring protection of online privacy. A possible remedy for the Japanese statute is to add services originating from foreign companies to a regulatory category in Japan’s already existing Telecommunication Business Act which requires operators to comply with communication privacy. Although domestic law generally has effects only within a nation, there is a clause in the Act on the Protection of Personal Information to apply regulations even to foreign countries’ business entities. I argue that such measures should be incorporated into Japan’s Telecommunication Business Act.