blue box

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An electronic device equipped with a tone pulsator that was formerly used to place free, illicit long-distance telephone calls by mimicking the tones sounded when operators routed such calls.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a blue coloured container used for the collection of household waste (such as tin cans and newspapers) for recycling by a municipal authority
• noun an electronic device used to bypass payment on a tone pulse telephone system