No more unaccessible battery products for me.
You could go with using land lines. Wait.... Those are easier to eavesdrop on than cell phones. All virtually anyone needs is a wrench, maybe a screwdriver, and a handheld test set like the phone guys use. With the good ones, you can't even hear someone 'clip on'. Once the cable pair your using is found, it can be used anywhere between the box at your house and the phone office. I doubt the NSA bothers with your physical wire pair though. They most likely have a way of remoting into the switch at your phone office.
Make your cell phone has a removeable battery.