How does a mobile phone work?

Your phone is a two-way radio that shouts to a tower up to a few kilometres away, proves who you are with a secret key, and hands your call from cell to cell without a click. Under the glass, the touch layer and the OLED screen, a phone is mostly battery.

Read how it works: How does a mobile phone work? · The history of the mobile phone · More boxes on Glassbox

Chapters in this interactive model

1. Inside a smartphone: A radio, a computer, a camera and a battery, squeezed into a slab less than a centimetre thick.
2. A city cut into cells: Why it's called a "cell" phone, and how your call jumps from tower to tower without dropping.
3. Voice and data on radio waves: How a phone packs bits into a wave, and why low bands travel far while high bands carry more.
4. From 1G to 5G: Each generation is a new rulebook for the radio. Speeds rose about four thousand times in thirty years.
5. What happens when you call: From tapping the green button to hearing "hello": a check on your SIM, a search for the other phone, and fifty packets a second.
6. Battery, radiation and what's left: Where the battery goes, why a weak signal drains it, and what phone radio can and can't do to your body.