Come June 19th, T-Mobile is celebrating Father’s Day with a one-day only promotion that discounts all of the company’s phones, including the priciest Android and BlackBerry models, at four-figures –that is right, free. Of course, such a sweet deal is attached to a big stipulation.

For those who are going to get a new line onto a T-Mobile family plan or want to switch over to the carrier with a family plan, the offer is awesome; otherwise, I doubt that many customers are itching to jump carriers just because of this promotion. iPhone lovers are staying with AT&T for the iPhone 4. Verizon is landing the Droid X and Droid 2, while Sprint is getting the Galaxy S Pro 4G.

This Saturday, starting at 8 a.m., simply visit a T-Mobile retail store and switch to any family plan, or add a new line to an existing family plan, and walk out of the store with a new phone for every new line with a two-year agreement - customer’s choice - while supplies last.