Both AT&T and Verizon are prepping new shared data plans that'll allow several devices on an account to share one bucket of data, and last week Verizon revealed that existing unlimited data customers upgrading to a subsidized device will need to switch to a shared plan once they're introduced. It doesn't sound like T-Mobile will be jumping on the shared data bandwagon any time soon, though.

T-Mobile CEO Philipp Humm recently spoke with The Seattle Times and said that he believes that the cell industry is "doing a mistake" by attempting to copy the shared voice minutes model. Humm explained his stance by using the example of a family with three devices on a shared data plan, saying that one person could quickly burn up the most of the allotment by watching an HD movie. The exec added that he doesn't think that a shared data plan "is a model that applies to the modern world" and that it's not a plan that he wants to offer because it could "create negative customer perception."

Humm also touched a bit on Windows Phone. When asked how T-Mobile's commitment to the platform has been working out, he said T-Mo has found new smartphone users enjoy the simplicity, design and ease of Microsoft's mobile OS. He added that he's "quite pleased" with sales of Windows Phones on T-Mobile and that he believes that Microsoft is pleased with T-Mobile.

Finally, it's hard to have a conversation about T-Mobile without mentioning the iPhone as of late, and so it shouldn't come as a shock to learn that the topic of Apple's handset came up during Humm's interview. When asked if Humm thought that T-Mobile needs to offer the iPhone, the exec said that the iOS handset is "a good and important smartphone," but he also posed the question of whether T-Mobile really needs to officially carry the iPhone or if it simply needs to open up its network to allow customers to bring their iPhones onto T-Mobile. Humm then mentioned that T-Mobile has had success in offering unsubsidized plans, which accounted for 45 percent of the carrier's growth.

T-Mobile has noted that it serves over one million iPhone users on its network, despite the fact that it's never officially offered the device, so obviously there are a number of people that have been attracted by T-Mo's unsubsidized plans. That said, I bet that there are quite a few folks that'd flock to Magenta if it put a subsidized iPhone on its shelves. Until that happens, though, T-Mobile's decision to put HSPA+ on some of its 1900MHz spectrum (which will give 3G service to unlocked iPhones) is the next best thing to officially offering the iPhone. If you'd like to read more of Philipp Humm's interview, which includes discussions on T-Mobile's recent layoffs and its effort to retain its brand as the affordable carrier, you can find the full talk at the Seattle Times link below.

Via TmoNews, The Seattle Times