It's not easy to get away with not having a smartphone in this day in age. While it's undeniable that most people need a smartphone to get through their day, not everybody wants to spend a significant amount of money on their phone or even go to a store to get all of their SIM card business squared away. In the interest of catering to the needs of the latter group, Microsoft is - for a short time - packaging the Lumia 550 with a T-Mobile SIM activation kit for no additional cost.
The SIM card will be shipping with your Lumia 550, letting you slip it into the device and get it activated without needing to leave the house. The SIM activation kit goes for just $20 on the T-Mobile store so that you won't be saving all that much, but every little bit counts. If you wanted to pick up a Windows 10 Mobile device but don't want to drop too much money on it, now would be a pretty opportune time to pick up the Lumia 550.