The rumors have been percolating up through the internet for months that Sprint (and parent company SoftBank) was nearing a deal to buy controlling interest in T-Mobile US, but a French company you've probably never heard of just threw a monkey wrench in the works. Iliad has offered $15 billion in cash for 56.6% of T-Mobile.

The proposed acquisition values T-Mobile at $36.20 per share (after the deal), which would be a good deal for current T-Mobile owner Deutsche Telekom. Iliad has made a name for itself in the French mobile market by offering steeply discounted prices, forcing the larger players to follow suit. It's actually similar to what T-Mobile has been doing with the Uncarrier strategy. Iliad says it already has the financing in place to make the deal happen if Deutsche Telekom agrees.

Working in Iliad's favor could be US regulatory agencies, which might look more favorably upon the Iliad deal. The acquisition by SoftBank would result in a Sprint/T-Mobile merger and one fewer wireless carrier in the US. Iliad is currently a non-entity in the US market, so there are no anti-trust worries. It's possible that Sprint could increase its offer to beat Iliad, but either way, things just got interesting.

[Wall Street Journal, Iliad (PDF) – Thanks Yann]