I ask this all the time but have yet to find anyone that has actually measured it. According to Snowden, basebands are still powered and operational even when t

I ask this all the time but have yet to find anyone that has actually measured it. According to Snowden, basebands are still powered and operational even when the main application OS (android/ios/etc.) are shut down. And a non-removable battery sure doesn't help that. Plus, he also says that the baseband often has its own separate connections to the GPS, microphone and camera and can operate them without the application OS involved. If the baseband is still powered, I can only assume it is simply sending (or responding to) periodic commands that do not require network authorization, which could possibly still let the network know where you are even without involving any roaming charges.