Definitive source is easy as shit - power off your phone, then see if it's drawing any power from the battery. If it's not, then it can't be remotely activated.

Definitive source is easy as shit - power off your phone, then see if it's drawing any power from the battery. If it's not, then it can't be remotely activated. Period, end of story. That's just flat out not possible. If we had the technology to receive wireless signals without using any power our cell phones would have batteries that last for weeks instead of a day.