T-Mobile USA is suing Starbucks, saying the coffee shop chain secretly colluded with AT&T to offer free WiFi Internet access in its cafes despite an exclusive agreement with T-Mobile.

In the lawsuit, filed late on Thursday in New York state court, T-Mobile alleges that AT&T and Starbucks Corp are not living up to an agreement the three companies reached over how Starbucks should transfer from its T-Mobile partnership to a new partnership with AT&T announced earlier this year.