Among US national carriers, T-Mobile and Sprint have long been the champions of unlimited data even as Verizon and AT&T have clamped down in recent years — but for T-Mobile customers, there's always been a catch: after a certain level, you get throttled down to glacial speeds. That changes today with the introduction of "Unlimited Nationwide 4G Data," an add-on for the company's voice / text plans that includes throttle- and cap-free access to its HSPA+ airwaves (which are now up to 42Mbps in many markets). The package costs $20 for "Value" plans — those that aren't tied to a subsidized device that you purchased directly from T-Mobile — and $30 otherwise, but the catch is that you won't have hotspot capability. If you still need that, you'll need to go back to a traditional plan that throttles once you reach 5 or 10GB, for instance. T-Mobile wasn't able to tell us specifically whether the plans would still be available once the company's LTE service lights up in the next few months, but a company spokesman noted that these aren't "promotional" rates — they're not going anywhere any time soon.

All-you-can-eat voice, text, and data without throttling would run an individual subscriber $89.99 a month on the new plan, which T-Mobile points out compares to $110 on both Verizon and AT&T at the 4GB level and $109.99 on Sprint with unlimited data (which is also unthrottled). Look for the new packages to become available for new and existing customers on September 5th.