What is a red box?

The term "red box" refers to a device used for hacking payphones. It would emulate the tones a payphone received when coins were inserted, allowing the user to make calls without actually paying. This manipulation involved emulated tonal feedback that indicated to the system that money had been deposited, thus granting access to service that was not actually paid for 1.

In another context, "Redbox" is a company that offers DVD rental services through vending machines. These machines are typically located outside convenience stores and supermarkets, providing a physical alternative to online streaming services by allowing users to rent movies on DVDs 2.