Squint enough and you'll see a cellphone consists of two primary chipsets: a main SOC/stack that runs the operating system, and a modem/software stack that push

Squint enough and you'll see a cellphone consists of two primary chipsets: a main SOC/stack that runs the operating system, and a modem/software stack that pushes cell packets. Power the phone down and you (may) fully shut down the OS/processor; you likely aren't powering down the modem.