SAN FRANCISCO -- For T-Mobile's next "Uncarrier" act, the company is broadening its Wi-Fi calling and text message feature, thanks in part to Apple's decision to include the feature in the latest iPhone .

Sarah Tew/CNET

"Uncarrier 7.0," as the company has dubbed its event on Wednesday, is less a shake-up of the industry and more augmenting a feature already available to millions of its customers.

The company on Wednesday announced a program, called "Wi-Fi Un-leashed" to get more of its customers on smartphones that are able to make calls and exchange text messages over a Wi-Fi network. That entails offering faster upgrades through its Jump early upgrade program.

"Wi-Fi Un-leashed is a game changer," CEO John Legere said in a statement. "This is like adding millions of towers to our network in a single day."

To ensure each customer makes the most out of Wi-Fi, T-Mobile also said it would offer a customized Wi-Fi router for free (with a deposit) tweaked to better work with its smartphones. T-Mobile has also signed a deal with GoGo inflight Wi-Fi service to offer free text messages, picturing messages, and visual voicemail in air on any US-based airline.

The increased focus on Wi-Fi calling and messaging is due to Apple's spotlight on the feature. But it's also a way for the company to shore up lingering concerns from consumers about the quality of its wireless service. While it has done a lot of strengthen its coverage and speed over the last two years, there remains coverage gaps in more rural areas and a bad rap from legacy customers who suffered through poor service in the past.

With Wi-Fi calling, T-Mobile can make the argument that call quality will remain strong wherever there is a nearby Wi-Fi network, particularly homes in weak coverage, or in parts of the house like a basement, where a cellular signal may fail to get through.

This is the sixth "Uncarrier" event and seventh program for T-Mobile, which has campaigned on shaking up the industry and upending the conventions of the wireless business. That includes the location of its event, based here instead of Las Vegas, which is where the rest of the US wireless industry is holding a confab at the CTIA trade show.

The impact of each Uncarrier event has diminished with each new program. Uncarrier 1.0 killed off contracts and the follow-up event introduced the early-upgrade programs, both of which have been adopted by its rivals. Uncarrier 5 and 6 consisted of a free seven-day trial and data-free music, which were nice bonuses for new and existing customers, but not a game-changer.

Still, T-Mobile can't stand still. Sprint has shown signs of life with its own aggressive slate of promotions, including a special lower priced $50 iPhone-centric service plan introduced after the iPhone 6 was unveiled on Tuesday. Sprint and T-Mobile, which saw their merger plans fall apart last month, have gone back and forth on various promotions.

T-Mobile's Wi-Fi calling feature isn't new, and many of its smartphones already offer the capability, with Apple playing catch up. The company said it has 20 million customers in its base with a Wi-Fi calling-capable phone. Apple highlighted as the sole US carrier currently offering the feature in its presentation on Tuesday. Along with the iPhone 6 and iPhone 6 Plus, older versions of the iPhone, going as far back as the iPhone 5C and 5S, would get the feature with the installation of the iOS 8 software upgrade.

But for customers with voice-over LTE, T-Mobile touts a seamless hand-off between a Wi-Fi call and a VoLTE call. In July, T-Mobile launched its voice-over LTE network across the nation, which is only compatible on specific smartphones. The iPhone 6 is among the phones that is compatible with VoLTE.

Verizon Wireless said it had no plans for Wi-Fi calling, insisting that its cellular coverage was sufficient. AT&T said it plans to offer the feature, but gave no time line. Sprint couldn't be reached for comment on its plans.

As part of the campaign, it will allow members who don't own a Wi-Fi calling-capable phone who are on the carrier's Jump upgrade program to immediately get a device, regardless of when they were supposed their upgrade. Customers who sign up for the Jump program can also immediately upgrade to a Wi-Fi calling-capable phone.

The catch is a customer has to sign up for the Jump program, which charges an additional $10 fee a month for the privilege of upgrading early.

T-Mobile is offering a "Personal CellSpot," which is a special Asus-built Wi-Fi router, for customers for free, although they have to pass the standard credit check for a new customer and put down a $25 refundable deposit. They also need a compatible smartphone. The router runs on the latest 802.11 AC Wi-Fi standard, offering up higher speeds.

The router is designed to recognize and prioritize T-Mobile calls, ensuring that a relative's "Warcraft" session isn't clogging up the bandwidth. The router can work alongside an existing Wi-Fi router in the home too.

T-Mobile had looked at femtocell technology, which acts like a mini cell-tower powered by your home Internet connection, but felt that using Wi-Fi would be simpler.

The GoGo partnership allows for limited use with text messages and visual voicemail -- a customer just needs to go online and sign in. T-Mobile customers looking to do more will still need to pay for inflight Wi-Fi service.

Overseas, T-Mobile customers will also be able to make calls back home over Wi-Fi for free.