Multiple choice

In a telephone, the dial tone has a frequency of _______.

  1. 1 Hz

  2. 13 Hz

  3. 33 Hz

  4. 133 Hz

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The standard North American telephone dial tone is a combination of 350 Hz and 440 Hz. However, in many technical training contexts, 33 Hz is historically associated with ringing signals or specific legacy signaling frequencies.