I have a Verizon iPad Air and put a T-Mobile sim card in it for the 200mb free data. Now that it is set up, if I decide to use another carrier for a while what do I have to do with the T-Mobile account? Would I cancel and delete and then have to get another sim card? Just pop it out and back in when I want to use it again (this seems to make more sense)? And if I don't use it for a while, will it eventually expire like the Verizon one would in 5 months?