The USB interface of an Android device is pretty complex ... with your device with ADB while configuring the internal modem ...

This discovery hinges on a mountain of work by a Chinese hacker [HandsomeYingYan], who’s figured out this stick runs Android ... modem chip, and its functions are limited to performing USB ...

A modem that plugs into the USB port of a computer. The term states only that the connection to the computer is via USB but does not imply which network service is supported. It often refers to a ...

Typically available as an external USB module, for desktop computers, the modem may also be available on a PCI or PCI Express (PCIe) card that plugs into an empty slot on the motherboard.