CEDIA ESPA EST Practice Test

Answer - B - Two frequencies combine to produce a tone in a telephone.

Key Takeaway: The tones in a telephone like the dial tone, common dialing sounds, busy, and off-hook, are recorded sounds embedded on a chip on the telephone’s circuitry. The dial tone is a combination of 350 Hz tone with a 440 Hz tone. A busy signal is a combination of a 480 Hz tone and a 620 Hz tone that is cycled on and off.