i just re-up my IUP for a Tmobile 12 Pro, does the sim card come 5G ready after phone being activated? Or do i have to go to Tmobile store and get their 5G sim card?
They will ship your iPhone with a 5G-compatible SIM already in the phone. Power on, device will activate on the network with your phone number, and you'll be good to go. (your old SIM in your current phone will quit working at that point)
Actually, SIMs aren't anything-G, most won't care, unless it's really old. They only tell your phone what network to look for and the ICCID number is to register on that network.
They will ship your iPhone with a 5G-compatible SIM already in the phone. Power on, device will activate on the network with your phone number, and you'll be good to go. (your old SIM in your current phone will quit working at that point)
No. Once you activate the new phone, the old SIM is effectively trash. You don't need to leave it in the phone that gets sent back to Apple. (they'll throw it out anyhow)
Once you activate the new SIM you may be hit with an upgrade fee. Try to use the old SIM and move it to the new phone. If your old phone is very old this will not work.