The sweet spot for 5G is midband and that's where T-Mobile is going to eat the other carriers' lunch. TMo has invested heavily in midband whereas Verizon rolled out this flashy mmWave spectrum at the Apple launch event that makes for good speed test screenshots but is not realistic for everyday use. It doesn't travel far enough. Midband is the balance between speed and actually having a signal that can traverse some distance and travel through walls/trees/etc.
Bottom line, do not waste your money or energy on a new SIM card. It's not necessary for all practical purposes, especially if you just use the eSIM. The support article makes it sound like you'll get a text if you need to upgrade your SIM. At that point, I would expect T-Mobile to incur that cost, not me.
Well that makes alot more sense!
So can I ask if the "midband 5G" is the 600Mhz spectrum ?
I ask because I used to own VHF and UHF NBFM voice repeaters on hilltops when I was younger.