Mobile Fundamentals · Inside a Phone · Lesson 1 of 4

What's Inside

Take a phone apart, part by part, on the simulated device.

Open it up

Under the screen, almost every smartphone is built from the same handful of parts. Brands and sizes differ, but the layout is very similar. Once you know the parts, most of what a phone does starts to make sense.

The SoC is the main processor. It runs the operating system, like Android or iOS, and every app you open. Working alongside it is the baseband, also called the modem. This is the processor that handles the connection to the cell network. Sometimes it is a separate chip, and sometimes it shares a package with the SoC. Either way it is its own processor running its own small operating system, apart from Android or iOS.

The baseband matters for security. It constantly reads signals arriving over the air from outside the phone, and its software is closed and hard for outsiders to audit. That makes it a favorite target for advanced attackers.

You'll also find flash storage, where your photos and messages are saved, a SIM tray, cameras, and a battery that takes up more room than anything else.

On the simulated phone, tap each part on the board and read what it does. Pay special attention to the Modem.

One chip to rule them

Desktop computers traditionally spread their work across several separate chips: one for the main processor, one for graphics, and others for memory and sound. Each chip takes up space, uses power and needs wiring to the others.

Modern phones pack most of that into one System on a Chip, or SoC. A single SoC usually holds the CPU cores that run your apps, a GPU for graphics and games, an image processor for the camera, and a neural engine for AI tasks like finding faces in your photos. Putting it all in one package saves space and battery, and lets the parts share data quickly.

Familiar SoC families include Apple's A-series in iPhones, Qualcomm's Snapdragon in many Android phones, and Google's Tensor in Pixels. Many Snapdragon chips also build in the cellular modem. Recent iPhones and Pixels use a separate modem chip instead.

The SoC matters for security too. On iPhone, the SoC contains the Secure Enclave, a walled-off area that protects your passcode and encryption keys. Pixels pair Tensor with a separate security chip called Titan M2.