Yesterday saw the long-overdue launch of the iPhone 5 on T-Mobile. And according to the so-called “un-carrier,” the device’s debut on the T-Mobile network made for a “gangbusters” day.

In a statement to AllThingsD, Chief Marketing Officer Mike Sievert said that the launch was “gangbusters for T-Mobile,” adding that there were “lines out the door […] at nearly all of our almost 3,000 stores nationwide.”

T-Mobile offers the iPhone 5 for a down payment of as little as $99.99, plus monthly payments of $20 over two years without a contract. The operative phrase here is, of course, “without a contract,” earning T-Mobile its “un-carrier” moniker.

T-Mobile also offers an iPhone trade-in program, which my colleague Bryan has deemed “respectable, and convenient.” Through this program, customers can bring their old iPhone 4 or iPhone 4S and avail of a new iPhone 5 at zero down plus monthly payments. On top of that, they can also receive up to $120 credit.

Check out T-Mobile’s iPhone 5 TV ad below, launched a day before the aforementioned “gangbusters” day.

If you can’t see the video embedded above, please click here.