In short: Under €15, Simsalasim at €10 is the best plan and the only one with truly unlimited data plus 100 countries. Every other plan in this price range has a fixed data allowance; the next true unlimited offer from a competitor (sim.de) only starts at €19.99.

  1. Simsalasim – #1.
    €10/month, unlimited data in 100 countries, calls, texts, and a number, on the Telefónica (O2) network.
  2. SIMon mobile – €11.99* / 80 GB.
    Vodafone network, lots of fixed data.
  3. 1&1 – €14.99* / 50 GB.
    Fixed allowance, with or without a term.
  4. Blau – €14.99* / 80 GB.
    Telefónica (O2) network, lots of fixed data.
  5. congstar Allnet Flat XS – €15.00* / 15 GB.
    Telekom network, fixed allowance.
  6. fraenk – €15.00* / 50 GB.
    App plan on the Telekom network.

Verdict: Under €15 only Simsalasim is truly unlimited (€10, with travel). Everyone else offers a fixed data pack; sim.de only becomes unlimited from €19.99. Simsalasim is cheaper and does more.

*Prices and offers can change over time (as of October 2026).