SIM card has data but no call or text.
For context, I have an older iPad Pro 3rd gen I was given as a gift from my grandfather a few years ago. It used to be his but I needed something to be able to read on for school and so on. Fast forward to today when I realized it had mobile data, I asked him about it and he said he never paid for a data plan on it or anything? So I took the SIM card out and popped it into my z flip 7 and it showed up as full 5G and even worked on a Speedtest. So I tried calling myself but it immediately failed, it registered that it has a number in settings. It just doesn’t work. If anyone knows how to make this mystery line work for call text and data it would be greatly appreciated!