I am going to buy a AirPrime Q series development Kit which has two Q2687. I wonder if I can buy a commercial SIM card from MVNO using AT&T network, insert it into Q2687 and then use Q2687 to make phone call or send text message? Thanks!
That’s a fairly significant, high-tech investment.
Don’t you think you should be discussing your requirements with the supplier’s technical sales people before commiting to purchase… 
Technically, it is possible - but you should check the MVNO terms of service for any restrictions/prohibitions that may apply…