Only several days have passed since Starbucks and AT&T officially made available free Wi-Fi to US customers (upon purchase, registration, and use of a Starbucks Card with corresponding rewards program), and already T-Mobile, the coffee chain’s pre-existing wireless Internet service partner, has presented a lawsuit in New York state court.

Reuters reported on T-Mobile’s filing Friday evening, in which the company claims that Starbucks “secretly colluded with AT&T to offer free Wi-Fi Internet access in its cafes despite an exclusive agreement with T-Mobile.” T-Mobile is said to be “seeking unspecified damages against Starbucks for breach of its contract and unfair competition.”

Upon announcement of the new deal, Starbucks said that it’s long-standing arrangement with T-Mobile would be phased out in 2008, a plan T-Mobile allows is true, though it says that the stipulations of said plan was that the original provider for Starbucks was to maintain “the exclusive right to ‘sell, market and promote its services’ in Starbucks stores until those stores were fully converted to the AT&T system.” The suit goes on to allege in greater detail that “Starbucks stores would be transitioned (away from T-Mobile) ‘on a market-to-market basis.’” T-Mobile stated that, as of Thursday, the original date of the suit, only locations within San Antonio, TX, and Bakersfield, CA, had completely made the transition.

Though T-Mobile may claim Starbucks has breached their previous agreement, it seems that the coffee giant can perhaps slide past negative judgement in court - if the case is to proceed that far. T-Mobile’s admittance that a gradual, market-to-market transition may well give Starbucks a wide enough window to respond with the technical argument that has followed those rules. It could be exceedingly difficult - save for a good supply of evidence of conflicting transgressions - for T-Mobile to secure a win.