I have a Verizon sim in my Air. I have ordered the T Mobile sim. If I try it and do not like the coverage or speed, can I go back to the Verizon sim? Or will I need a new Verizon sim?
Yes you can. The iPad is unlocked and you can use the Verizon, T-Mobile and AT&T SIM's at anytime. If your Verizon SIM has been activated it will be de-activated by Verizon if you do not use it within 5 months, which would require you to get another one.