Today’s launch in Chicago; Reno, Nev.; Fresno and Sacramento, Calif.; and the region surrounding Los Angeles (though not in LA itself) – coupled with activations on Monday in Atlanta, Seattle and Minneapolis – bring its total upgraded footprint to 23 markets covering more than 100 million people. While T-Mobile doesn’t sell the device yet, customers with unlocked iPhones can use them on the carrier’s network. But only in areas where the upgrade is complete will they get anything beyond a 2G connection.

Though in the rest of country the network officially hasn’t seen the upgrade – which will move a portion of T-Mo’s HSPA+ network to the 1900 MHz PCS band – customers with unlocked iPhones have reported seeing HSPA+ signals from New York to LA, cities where their Apple devices would normally be restricted to pokey 2G speeds. Right up to its launch this week, Chicago was a hotbed of signal sightings so T-Mobile obviously has many more markets in the works.

T-Mobile is rushing to complete its network reconfiguration for a number of reasons. Not only will it be fully compatible with the iPhone’s 2G and 3G radios when it starts selling the device next year, but the sooner it relocates HSPA+ to the PCS band, the sooner it can start building its new LTE network.

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And depending on location, those demo phones won’t be limited to 2G-only data speeds. In a blog post going up Monday morning, T-Mobile reveals it has activated its HSPA+ network in iPhone-friendly bands in parts of New York City, Seattle and Las Vegas. T-Mobile has even developed an iOS version of its Bobsled VoIP calling app to support the 1 million “unofficial” iPhone users it already has.

Essentially, T-Mobile is doing everything it can to welcome iPhone owners onto its network, especially now that AT&T has begun unlocking the devices once its customers fulfill their contracts.

Why the sudden push? T-Mobile is in the process of revamping its mobile data networks, which will allow it to launch LTE next year. But there’s a big a side benefit to the project: it is aligning its data networks with AT&T’s, meaning any device that works on Ma Bell’s networks will work on T-Mobile’s.

We talked to T-Mobile CTO Neville Ray and he confirmed that in areas where it’s turned up HSPA+ in the PCS band, there’s no longer any technological barrier preventing the iPhone from meeting its full potential on T-Mobile’s network (though some services won’t carry over such as visual voicemail). At GigaOM’s Mobilize conference on Sept. 20, Ray plans to share the details of T-Mobile’s network overhaul, but this week he gave us a bit of a preview.

T-Mobile has already shut off large portions of its 2G GSM networks in the 1900 MHz PCS band across 80 percent of its footprint, clearing those airwaves for HSPA+, Ray said. In many cases T-Mobile has enough free PCS spectrum to replicate its current dual-carrier HSPA+ configuration in its old 2G bands. That means if the new version of the iPhone supports dual-carrier (like the new iPad released this year), T-Mobile will be able to deliver theoretical maximum speeds of 42 Mbps to the device.

Ray said internal testing of the current iPhone 4S comparing performance on T-Mobile and AT&T’s networks shows that T-Mobile is achieving speeds 70 percent faster than its rival, even though the current iteration of the device doesn’t support dual-carrier. In addition to its network, Ray said, T-Mobile’s big lure will be its liberal data plans. Not only does it offer some of the biggest smartphone bang for your buck in its tiered plans, T-Mobile recently brought back an unlimited data option.

But all of this moot until T-Mo’s network upgrade is complete. LTE is scheduled to go online in the second half of 2013, but Ray said iPhone users won’t have to wait that long. Deploying LTE is the last step in its multi-part overhaul. “We’ll have a material footprint on HSPA+ at 1900 MHz by the end of the year,” Ray said.

Ray wouldn’t define “material,” but he said T-Mobile would begin making even more aggressive moves to lure unlocked iPhone customers during the holidays. Of course, at a certain point the question of locked or unlocked becomes moot.

As I’ve written many times before, when T-Mobile’s HSPA+ network at PCS gets big enough, Apple will start distributing its iconic device directly through the operator. Though Ray won’t comment on any possible negotiations with Apple, a deal between the two is certainly no stretch of the imagination. Despite its status as the No. 4 operator in the U.S., T-Mobile is still one of the world’s largest carriers. As soon as the last technical barrier disappears, Apple will welcome T-Mobile into the iPhone family with open arms.

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Verizon Wireless’ new LTE network may be experiencing the biggest growing pains among U.S. operators, but T-Mobile’s brief network outage Monday night showed that even an established technology like HSPA+ isn’t free from problems.

Last night T-Mobile experienced intermittent data outages in different parts of the country, which led customers to flood T-Mobile’s Twitter feed and support forums with questions and complaints. T-Mobile confirmed the outage in a tweet at 7:48 p.m. PT, and 90 minutes later it tweeted that the network problems had been resolved and service restored to normal.

T-Mobile didn’t state publicly what the cause of the outage was, but if I can hazard a guess: T-Mobile is currently engaged in a major network overhaul, switching out major portions of its GSM network for new Ericsson and Nokia Siemens Networks HSPA+ base stations. At the same time, it’s retiring portion of its current HSPA+ network in the 1700 MHz/2100 MHz (AWS) band in order to make room for its new LTE systems.

It just so happens the first phase of that network reconfiguration is scheduled to begin this month with an initial 2500 cell sites. You can’t move that much hardware around with out experiencing some problems, so we’re probably going to see several more hiccups on the T-Mo network over the next year.

T-Mobile image courtesy of Flickr user swruler9284

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T-Mobile CTO Neville Ray

T-Mobile isn’t just launching a sizable LTE network in 2013, it’s becoming the Grim Reaper for 2G technology as we know it. In an analyst conference call on Thursday, T-Mobile unveiled a plan to radically reshape its networks, shutting down the majority of its 2G GSM capacity so it can focus almost entirely on 4G. As a result T-Mobile will get a bigger, badder mobile broadband network and, to boot, will almost certainly land the iPhone.

With this new network configuration, T-Mobile is pulling a technological coup. Though it is spectrum-poorest operator of the Big 4, it will wind up with a higher-capacity LTE network than Sprint and one with comparable capacity to AT&T, while still being able to milk a massive HSPA+ network for years to come. In the process, T-Mobile is calling into question the so-called spectrum crisis. While other operators are desperately searching for new airwaves, T-Mobile found its future growth spectrum sitting right under its nose. Consumer groups and regulators are almost certainly going to ask why AT&T and Verizon Wireless don’t do the same.

The network numbers T-Mobile CTO Neville Ray revealed at the call were surprising: 90 percent of the carrier’s data traffic and 50 percent of its voice traffic are running over T-Mobile’s HSPA+ networks. That means its GSM networks are languishing even though they occupy half of T-Mobile’s average 54 MHz of spectrum per market. T-Mobile’s answer is to shut them down, clearing the way for LTE and more HSPA+.

T-Mobile plans to sunset between two-thirds and three-quarters of its GSM channels in the PCS bands leaving, only a modicum of 2G bandwidth left for older phones that don’t sport 3G or 4G radios and to support basic data services for its machine-to-machine communications business. All of that capacity would then be turned over to HSPA+, creating a mobile broadband network on PCS almost as large as the one it currently runs on its advanced wireless service (AWS) frequencies. Moving HSPA+ to PCS opens up many doors for T-Mobile, most notably the ability to support any iPhone Apple makes for the U.S. market.

But T-Mobile won’t shut down HSPA+ at AWS completely. It will turn off some of that capacity and combine the remnant airwaves with the AWS licenses it took from AT&T as a consolation prize for their merger’s failure. It would then use that capacity to build a 10MHz-by-10MHz LTE network over 50 percent of its mobile broadband footprint. That would give it the same capacity as Verizon’s LTE network today and double that of the LTE network Sprint plans to launch this summer. In the remaining half of its network T-Mobile can only support a 5MHz-by-5MHz carrier, which would make its capacity configuration similar to AT&T’s. But keep in mind, T-Mobile has a fraction of the customers of Ma Bell and Verizon – it can make 5×5 go a long way.

Ray and CEO Phillip Humm said T-Mobile USA is still on the hunt for more spectrum, and ideally it would like to lock down more AWS airwaves to create a massive 20MHz-by-20MHz LTE network. That seems unlikely considering that its competitors are quickly scooping up what unused airwaves remain in the market, but T-Mobile is also challenging those deals.

Though Humm and Ray didn’t discuss it in the call, there’s always the possibility of repeating its network cannibalization feat at a later date to capture even more mobile broadband capacity. As more voice traffic moves to HSPA+, and more data traffic moves to LTE, T-Mobile could shut down its GSM network almost entirely and continue the HSPA’s shift down to PCS, which would in turn clear more AWS airwaves for LTE.

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