Verizon today lit up what it called the “first commercial 5G network on the globe,” but T-Mobile CEO John Legere was not impressed, unleashing a trolling tweet thread roasting the mobile giant Monday.

The Verizon service is now live in parts of Houston, Indianapolis, Los Angeles and Sacramento. The race to 5G has been highly competitive among carriers, and while Verizon has planted its flag as the first to offer a next-generation home network, its mobile 5G plans remain to be seen until next year, as The Verge notes.

In his thread, Legere drops an asterisk next to Verizon’s new 5G product, and says T-Mobile has a different 5G vision that will scale faster than Verizon’s.

I cannot begin to explain how important 5G is going to be for this country, so I have to say congrats to Verizon on delivering its 5G* Home Service today. It doesn’t use global industry standards or cover whole blocks and will never scale… but hey, it is first, right?! 🤷‍♂️ — John Legere (@JohnLegere) October 1, 2018

We have a different vision! @TMobile will have 5G across the country – and the New T-Mobile will build a 5G network that’s both broad & deep – NATIONWIDE. Ask Verizon if their proprietary non-standards 5G* will eventually work on any phones in the market…. (SPOILER: they won’t) — John Legere (@JohnLegere) October 1, 2018

Verizon says,“there’s 5G & then there’s @Verizon 5G*” – What they mean is Verizon 5G* is available… in tiny pockets of neighborhoods… if you don’t have 🌲s nearby… or appliances in your house… or walls… just 👀 at the #VerizonFAQ… 😂 pic.twitter.com/s4TJIiPtwJ — John Legere (@JohnLegere) October 1, 2018

I still have so many unanswered questions… for instance, do you have a better chance of getting @Verizon’s 5G* if you wrap your house in tin foil?? These are the important questions that @verizon still needs to answer. 😂 #VerizonFAQ pic.twitter.com/01yhoJpXfP — John Legere (@JohnLegere) October 1, 2018

T-Mobile is working on its own plan for nationwide 5G, and that is a big reason why it is acquiring former rival Sprint. In recent months, T-Mobile has inked deals with Ericsson and Nokia totaling $7 billion to help build out T-Mobile’s next-gen network.