T-Mobile is offering customers of other carriers a free mobile hotspot device, together with a free data plan lasting 30 days or 30GB, whichever comes first.

The hotspot is similar to devices that sell for around $30, and T-Mobile says you can keep it afterwards – though there’s likely a catch to that…

The offer is the latest incarnation of T-Mobile’s Test Drive program, intended to let customers of rival carriers see for themselves how the company’s data coverage and speeds compare. It’s aimed at those currently with Verizon, AT&T, Sprint, Xfinity Mobile, or smaller carriers.

Back in 2014, the T-Mobile Test Drive let you get an iPhone 5s on loan for a week. The hope was that people would be sufficiently impressed to buy the phone as well switch networks.

The 30-day/30GB free trial

The latest deal isn’t intended to sell you any hardware, but rather to persuade you to switch your contract from your existing carrier to T-Mobile.

The benefit of the hotspot approach is that you can continue to use your own phone.

T-Mobile is amping one of its original Un-carrier moves — Test Drive —and giving consumers a chance to try the Un-carrier’s expanded LTE network free for up to 30 days using their own smartphone. Plus, T-Mobile is launching a major new ad campaign underscoring the company’s newest, most powerful signal. No signal goes farther or is more reliable.

84% of people want to try a wireless network before they switch carriers. Yet, wireless is one of the only industries in the world that forces customers to buy before they try. T-Mobile is out to end this backward practice, in part because the Un-carrier has nothing to hide.

Free mobile hotspot, with a likely catch

T-Mobile says you can return the device or not as you like at the end of the trial.

However, before you start thinking that’s a sweet way to score a free mobile hotspot device, it’s a pretty safe bet that you can’t use it with any other carrier. But still, 30GB of free data is not to be sniffed at.