In telephony, special information tones are a series of three audio tones, which indicate that a telephone call cannot be completed and is typically followed by a recorded announcement explaining the reason for the call failure.
Special information tones are a series of three audio tones. This is in telephony. A telephone call cannot be completed. This is what three audio tones indicate. A telephone call is typically followed by a recorded announcement. This is what three audio tones indicate. This recorded announcement is explaining the reason for the call failure.