The offer starts Thursday and runs through the end of the year. If you sign up, T-Mobile will send you a WiFi hotspot and SIM via two-day shipping. You'll be able to connect pretty much whichever phone you like to the hotspot to see how well the T-Mobile network performs, but it might be annoying to cart around an extra device for a month.
If you gobble up 30GB of data before the 30 days are up, your trial will end at that point. There's a limit on video too, as it typically streams at a maximum resolution of 480p. You also get a measly 200MB of roaming data.
The company has run similar trials before. In 2014, it let potential customers borrow an iPhone 5 for a week to see how much they liked the handset and to check out T-Mobile's LTE network. It placed a $700 hold on participants' credit cards, but the signup page for the latest trial doesn't mention anything about a hold or fees should you damage or lose the loaner hotspot. It seems likely you'll see more fine print when T-Mobile gets in touch, should you sign up. If you have a friend who completes the trial, T-Mobile says you can borrow their hotspot and use it with another SIM card the company will send you.
Combined with improved customer service and new entertainment perks the company revealed at its latest Uncarrier event, T-Mobile will hope the trial will encourage those curious about the network to sign up to a plan.