So yesterday I decided to activate the data on my lovely iPad Air 2 wifi+celllar and chose T-Mobile because of their 5GB data deal. So when I entered all my information, created a new account, it said "activating" then popped up "couldnt activate cellular data on network." I called Apple and was put on hold for a half hour so I hung up and called T-Mobile. Recieved a rep who was very nice and needed the ICCID number, however because my phone failed to activate properly, I never recieved a ICCID number in my About menu (my guess is when you activate on a carrier it encodes the SIM with a ID number for that carrier, because my SIM didnt activate properly, mine was never properly encoded). Everything was set up correctly in T-Mobile's system, I had a plan, account, phone number, etc. I wanted to start over with the setup, but the card wouldnt let me. The iPad registered as having been activated and gave me standard enable/disable LTE menus and such, but carrier was "unknown", still no ICCID number, and it just said "Searching..." in the top left side. The rep said I would have to go to the Apple store. So today I went to the Apple store and after waiting a hour explained the whole complicated issue and got them to give me a new SIM, the Cellular menu reset to "Set up Cellular" and balance was resored... so I thought. There was no way to connect my prepaid plan I set up with the old SIM to my new SIM via the menus! I called T-Mobile again and the rep was very rude and insisted that I needed to get a T-Mobile SIM card and that my previous SIM was a T-Mobile card and he was looking right at a T-Mobile SIM number and I was wrong (I'm guessing that a T-Mobile number was generated during my "half activation" yesterday). I asked to be trasfered to T-Mobile tech support and tech support said she can only enter a ICCID (which I didnt have because the new SIM wasnt coded as T-Mobile) or a T-Mobile SIM number. So here I am day 2 of paying for data I cant access. There's a T-Mobile store about 15 min walk from my apartment so I can get a card, but I'm just frustrated that my very expensive product doesnt work as advertised. ---------- I should also add nobody knew anything about how the Apple SIM worked. Including a "Geinus" who said "this is my first time actually seeing on of these".