ZyXEL Communications Comet 3356, User Manual

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54 Voice Operation
10
Voice Operation
Voice mode refers to the Comet’s ability to digitize incoming voice messages, which the
computer stores and forwards. It also means the modem can playback the recorded
digitized voice either off-line for local message listening or on-line for a message
announcement. For interactive voice applications, DTMF tone detection capability is
important so a computer can react according to the remote caller's touch tone input.
The modem is configured into Voice Mode (modem models not supporting business
audio) or Voice/Audio Mode (modem models supporting business audio) in response to
the AT #CLS=8 command, and this mode is composed of the Voice and Audio sub-
configurations as described in this section. Additional voice/audio AT commands are
available to support selection of operational parameters from both inside and outside
the Voice/Audio Mode.
a) Voice Sub-Configuration. Enhanced Adaptive Differential Pulse Code Modulation
(ADPCM) coding and decoding of analog voice is accomplished with a 7.2 kHz
sampling rate and 2 or 4 bits/sample quantization, and supports efficient compression
and decompression of digitized voice. Additionally, the Voice Configuration supports
concurrent tone generation/detection capabilities.
b) Audio Sub-Configuration (Available Only for Modem Models Supporting Business
Audio). Linear PCM coding and decoding of analog audio is accomplished with 7.2
kHz or 11.025 kHz sampling rates and 8 bits/sample quantization, and supports superior
sound quality as compared to ADPCM. With a sampling rate of 7.2 kHz, the Audio Sub-
configuration supports concurrent tone generation/detection capabilities. With a
sampling rate of 7.2 kHz or 11.025 kHz, this sub-configuration can be used to record
and playback monophonic data in 8-bit unsigned linear PCM format.
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The Voice/Audio Mode (i.e., either sub-configuration) supports three submodes once a
voice connection has been established (refer to the descriptions of the #CLS command):
Online Voice Command Mode, Voice Receive Mode, and Voice Transmit Mode.
Determination of whether operation takes place in the Voice sub-configuration or the
Audio sub-configuration is made by use of the #VBS and #VSR commands (refer to the
descriptions of these commands).
9.1 VOICE/AUDIO SUBMODES
9.1.1 Online Voice Command Mode
Online Voice Command Mode is the default Voice submode entered when the #CLS=8
command is issued, and may also be entered from Voice Receive Mode or Voice
Transmit Mode. Entry into Online Voice Command Mode is indicated to the DTE via