Voice Record
To begin recording of a message received via a handset or microphone,
the DTE must configure the modem for Voice Mode (#CLS-8), and select the
proper relay setup (#VLS) to instruct the modem whether to use the auxiliary
device. The modem responds to the #VLS command by issuing a relay activate
command to select the input device. When a device other than the telephone
line is selected, the modem immediately enters Online Voice Command Mode
(indicated by VCON). DTMF detection is therefore enabled as soon as the
DTE selects the device, such as a handset, although the user still needs
to physically pick up the telephone and "press buttons." Even if the
DTE has not entered Voice Receive or Transmit Modes (#VTX or #VRX), these
DTMF tones are delivered via shielded codes identically to when a physical
telephone connection exist but the DTE has not yet commanded receive or
transmit.
When the DTE decides to record the message, it issues the #VRX command and
upon command receipt, the modem immediately switches to Voice Receive Mode.
Since the microphone or handset is switched in, the modem immediately issues
the CONNECT message indicating that the modem has switched to Voice Receive
Mode and is beginning the transfer of ADPCM voice data as well as shielded
DTMF tones, and other tones and statuses.
In this recording state, the modem (if so configured) monitors for line
silence. If the #VSP period expires, the modem sends the <DLE> or <DLE>s code
to the DTE.
Recording can be canceled if:
1. The DTE sends any character to the modem. This is the key abort, and
is the normal method of terminating the receive mode.
2. The S30 deadman timer expires.
Shielded DTE Code Command: <DLE><ETX>
Description: Terminate - Sent during Voice Transmit Mode to indicate
that the DTE has finished transmitting a voice message. The modem completes
transmission of any remaining data in the voice transmit buffer before responding
with the VCON message and entering Online Voice Command Mode.
Note: This command is ignored by the modem when not in Voice Transmit
Mode.
Shielded DTE Code Command: <DLE><CAN>
Description: Cancel - Sent during Voice Transmit Mode to indicate that
the DTE <DLE><CAN> has finished transmitting a voice message and
wants the modem to discard any remaining data in the voice transmit buffer.
The modem immediately purges its buffer, and then responds with the VCON
message entering Online Voice Command Mode.
Note: This command is ignored by the modem when not in Voice Transmit
Mode.
Shielded DTE Code Command: <DLE><p>
Description: Pause - Sent during Voice Transmit Mode to force the modem
to suspend sending voice data to the selected output device(s). Any data
currently in the voice transmit buffer is saved until either a resume (<DLE>r),
or cancel <DLE><CAN>, is received, in which case the data is
lost. If a <DLE><ETX>is received during the paused state, the
modem processes it normally, and also automatically resumes transmission
of the data left in the buffer (appended with <DLE><ETX>). Any
other data received from the DTE while in this paused state is placed in
the transmit buffer according to available space, with flow control active.
Note: This command is ignored in other voice submodes.
Shielded DTE Code Command: <DLE><r>
Description: Resume - Sent during Voice Transmit Mode to force the modem
to resume sending voice data to the selected output device(s). Any data
currently in the voice transmit buffer is now played. (This command is ignored
in other voice modes.) The pause and resume commands are different
than a simple suspension of data; data in the buffer is "frozen"
and not played when the DTE pauses.
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