I have a BT Sim card in my tablet... It was working fine, made phone calls, used it to down load app etc. Then mainly used the tablet in the house, using the WiFi Now I find that for some reason I can no longer make phone calls or us the Sim for data. Any suggestions how to put this right... Without rebooting which is what I think may have caused the problem.
Check your "MyBT" in case there are any problems with your said SIM.
Oh, and rebooting an iPad will not cause any problems as far as I understand. Firstly though, why not simply power down, wait a minute and then power up again. That sometimes clears any of the simpler problems.