Tele-Communication (Telecom) Terms Glossary and Dictionary
Dial Tone is sent to a calling customer or operator to indicate that the receiving end is ready to receive dial pulses or DTMF signals. It is used in all types of dial offices when dial pulses are produced by the customer's or operator's dials. Normally dial tone means that the entire wanted number may be dialed; however, there are some cases where the calling party must await a second dial tone or where an operator, after dialing an initial group of digits, must wait for a second dial tone before the rest of the number can be dialed. Some dialing switchboards are arranged to permit listening for dial tone between certain digits. Dial Tone is 350 Hz and 440 Hz held steady at -13 dBm0/frequency.