O2/Telefónica

Telefónica operates as O2 in the UK and other markets, making it one of Europe's largest carriers by reach and infrastructure. Their eSIM travel plans explicitly support hotspot tethering, with data packages designed for tourists and business travelers moving between countries. Coverage spans 200+ destinations with consistent local speeds in major markets.

Works well for travelers who value a carrier with physical retail presence and local support in multiple countries. O2/Telefónica's advantage lies in regional strengths, particularly strong in the UK, Spain, Germany, and Latin America, where you can often use them as a local SIM alternative rather than a pure roaming solution. Global coverage is broad, though speeds and pricing vary by destination.