Answer tone
Encyclopedia
Answer tone is a feature of wireline modem
s.
The answer tone is the first signal sent by the answering modem after the billing delay. In its most basic form, it is a single continuous tone with a frequency of 2100 Hz (or 2225 Hz for Bell modes).
It is the tone heard by the caller after dialing the number.
The plain 2100 Hz tone is meant to disable echo suppressor
s on international trunk connections. It may include 180° phase reversals at intervals of 450 ms to disable network echo cancellers. It may also be modulated by a low frequency signal to indicate ITU-T
V.8 capability.
Modem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
s.
The answer tone is the first signal sent by the answering modem after the billing delay. In its most basic form, it is a single continuous tone with a frequency of 2100 Hz (or 2225 Hz for Bell modes).
It is the tone heard by the caller after dialing the number.
The plain 2100 Hz tone is meant to disable echo suppressor
Echo suppressor
An echo suppressor is a telecommunications device used to reduce the echo heard on long telephone circuits, particularly circuits that traverse satellite links...
s on international trunk connections. It may include 180° phase reversals at intervals of 450 ms to disable network echo cancellers. It may also be modulated by a low frequency signal to indicate ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
V.8 capability.