Story highlights T-Mobile to offer free cell spots that plug into wireless networks to extend coverage

It will also support new phones that allow calls to jump from WiFi to a cell network

On planes with GoGo WiFi service, customers will be able to text and check voice mail

T-Mobile wants to beef up its cell coverage by thinking small and piggybacking on your Internet service.

The carrier is offering its customers a free personal cell spot -- a router that plugs into an existing broadband connection to improve mobile phone coverage while at home. All new smartphones purchased through T-Mobile will allow phone calls and texts over WiFi. And as mentioned in Apple's announcement Tuesday, T-Mobile will be the first carrier to support seamless switching between WiFi and cellular networks, so you don't have to hang up and redial when you leave the wireless area. For now, the switching capabilities will only be available for the iPhone 6 and 6 Plus.

Why is T-Mobile pushing WiFi connections so heavily?

"My answer is, why the f*** not?" said T-Mobile President and CEO John Legere, who announced the news at a press event in a San Francisco bar Wednesday.

Legere took the stage in pink shoes and a leather jacket, dropping his signature bad words, jokes and digs at competitors. The carefully crafted edginess is all part of the fourth-place carrier's "Uncarrier" marketing blitz, which positions it as the underdog taking on Verizon, AT&T and Sprint.

Personal cell extenders aren't new, but T-Mobile says theirs are not the same products you can buy in stores. T-Mobile claims that one of these custom devices, which usually retail for around $200, can cover a phone up to 3,000 feet in any direction -- hundreds of feel farther than existing cell spots.

"We've injected a secret sauce that prioritizes voice calls," said Neville Ray, T-Mobile's chief technology officer. That means that if someone is streaming video on a WiFi network while another person wants to make a call, the video may be slowed so that the phone call gets more bandwidth.

The large black box has three external antennas, plugs into an Ethernet cable and can be used instead of existing routers. There is a $25 deposit for the box.

T-Mobile is also bringing (limited) WiFi access to the skies. On planes that have GoGo InFlight Wireless service, T-Mobile customers will be able to send and receive texts and listen to voicemails for free. The technology already exists to let passengers make phone calls, but a tangle of airline and FAA rules -- not to mention potential backlash from other fliers -- is limiting this feature to quiet activities.

Legere is ambitious and vocal about his desire to overtake the top three cell companies, which he calls the "Three Stooges."

"T-Mobile just had its biggest month in company history," said Legere. "We will overtake Sprint this year ... next on our list is AT&T."