About the company:
T-Mobile has a pretty known presence in the digital sphere, only consumers and regular businesses see the tip of the iceberg. The amount of hardware, services, and abstraction layers on abstraction layers is mind-boggling. But also really appealing for a nerd like me, even though I'm "just" a developer within this company, you get to think like an architect. To whom belongs this responsibility, where does this data live, where does it SHOULD live, etc etc etc.
I'm currently habituating the Red team, within Operational support services we have 3 RGB teams. As our decision name states, we create, manage and support operational services, so all services keep other services in the air. The scale on apps is quite extensive, my team alone is responsible for more than 18 apps, nodeJS, Rails, Elixir or just bash scripts, all need to be done. Even though I'm quite an experienced dev, there is much you can learn here. It's a nice place to be.