voice-cmds.html

VoiFax is a program that manage voice/data/fax modem in the same manner of vgetty and mgetty.VoiFax

the code is sent again as often as once every 4 seconds.

</td></tr><tr><td> &lt;DLE&gt;d
</td><td><b>Dialtone</b>.
Sent in Voice Receive Mode when dial tone is detected after
any remaining data in the voice receive buffer. The modem sends the
&lt;DLE&gt;d code every 3 seconds if dial tone continues to be
detected and the DTE does not react. This allows the
DTE the flexibility of ignoring what could be a false dial tone detection.

</td></tr><tr><td> &lt;DLE&gt;e
</td><td><b>European Data Modem Calling Tone</b>.
Sent when the V.25 1300 Hz Calling
Tone (Data Modem) is detected in a voice submode. The
modem assumes that the calling tone is valid, and sends this code only
after 4 seconds of proper cadence has been detected.
If the DTE does not react to the &lt;DLE&gt;e and calling tone continues,
the code is sent again as often as once every 4 seconds.

</td></tr><tr><td> &lt;DLE&gt;f
</td><td><b>Bell Answer Tone</b>.
Sent when Bell 2225 Hz Answer Tone (Data) is detected.
If the DTE fails to react to the code and the modem
continues to detect Answer tone, the code is repeated as often as every 1/2
second.

</td></tr><tr><td> &lt;DLE&gt;h
</td><td><b>Hung Up Handset</b>.
Sent immediately when the modem detects that the local
handset has hung-up (i.e., has transitioned from off
hook to on-hook) while in any of the three voice submodes.

</td></tr><tr><td> &lt;DLE&gt;o
</td><td><b>Overrun</b>.
Sent in Voice Receive Mode if the voice receive data buffer
overflows, in which case, the latest data is lost in
favor of retaining the oldest data in the buffer. (The DTE may not have
been reading data from the modem lately.) The modem
inserts the &lt;DLE&gt;o at the end of the buffer, thus marking the location
where data was lost by the DTE. The modem does not append
&lt;DLE&gt;o codes to the buffer contiguously. If more than one data byte
is lost before the DTE begins reading again, there is
only on &lt;DLE&gt;o code in the data stream. However, if the DTE resumes
reading, and then once again allows the buffer to overflow,
a new &lt;DLE&gt;o is appended to the data by the modem.
Thus, the &lt;DLE&gt;o does not indicate how many bytes of contiguous data
has been lost, but may report multiple gaps of lost data in the data stream.

</td></tr><tr><td> &lt;DLE&gt;q
</td><td><b>Quiet</b>.
Sent in Voice Receive Mode following any remaining data in
the receive voice buffer when the silence detection timer
(#VSP) expires and there has been voice data passed to the DTE.
Note that with #VSS=0, the Quiet message never occurs. But
with silence deletion turned on, #VSS may not in itself be sufficient
since "cracks and pops" for a short duration directly
after a connection should not be considered voice. In general,
&lt;DLE&gt;q is sent if first there was sound, and now there is no
sound, and means that somebody has stopped talking, and according to the
criteria selected in the #VSP and #VSS settings, is
probably not going to start again. If the DTE ignores the &lt;DLE&gt;q code,
the modem automatically resets its timer and sends the
code again if the #VSP time period again expires. This allows the DTE time
to react to what may be a false silence detection.
</td></tr></tbody></table>

</p><p>

<table border="1">
<caption>Table 8-2. Shielded Codes Sent to the DTE (Cont'd)</caption>

<tbody><tr><th>Code Sent to DTE
</th><th>Meaning

</th></tr><tr><td> &lt;DLE&gt;s
</td><td><b>Silence</b>.
Sent in Voice Receive Mode after the silence detection timer (#VSP) expires
and if valid voice has not been detected (#VSS).
In general, &lt;DLE&gt;s is sent if no sound was detected at all.
This differs slightly from Quiet (&lt;DLE&gt;q) in that it can
be used by the DTE in its discrimination algorithms as a means
of determining if anything at all is coming from the remote
station. If the DTE ignores the &lt;DLE&gt;s code, the modem automatically
resets its timer and sends the code again if the #VSP
time period again expires. This allows the DTE time to react to what may be
a false detection of silence.

</td></tr><tr><td> &lt;DLE&gt;t
</td><td><b>Handset Off-Hook</b>.
Sent one time when the local handset transition from on-hook to off-hook
is detected in any of the three voice submodes.

</td></tr><tr><td> &lt;DLE&gt;u
</td><td><b>Underrun</b>.
Sent in Voice Transmit Mode when the voice transmit buffer becomes empty
without receiving a &lt;DLE&gt;&lt;ETX&gt; or &lt;DLE&gt;&lt;CAN&gt;
command first. The modem remains in transmit mode, but issues
the &lt;DLE&gt;u to indicate that silence is being generated. When
the DTE resumes sending bytes, the modem allows a small number of bytes to 
build up in the buffer before re-enabling the transmitter
to avoid repeated underruns. However, with the underrun condition,
the modem does not wait for the XOFF threshold (or timer)
to be met before resuming, as it does on an initial transmit or resume
operation because the remote listener may be unaware
of the underrun, and keeping the silence short may serve to mask
the underrun altogether.

</td></tr><tr><td> &lt;DLE&gt;&lt;ETX&gt;
</td><td><b>End of Stream</b>.
&lt;DLE&gt;&lt;ETX&gt; is sent to denote the end of a voice data stream,
similar to fax Class 1 and 2. This occurs in Voice
Receive Mode only after the DTE issues the key abort.
</td></tr></tbody></table>

</p><h4>8.2.5. Shielded &lt;DLE&gt; Commands from the DTE</h4>

Most commands issued for voice are implemented as extensions to the AT
command set, and are accepted only if the modem is in
a valid command mode, such as Online Voice Command Mode. However, there
are some operations which are available to the DTE
without necessitating a switch to Online Voice Command Mode.
The most obvious of these is the &lt;DLE&gt;&lt;ETX&gt; which the DTE issues
during Voice Transmit Mode to terminate an output message. Table 8-3 lists
shielded &lt;DLE&gt; commands recognized by the modem.

<h4>8.2.6. Voice Record</h4>

To effect 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
exists but the DTE has not yet commanded receive or transmit.<p>

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.</p><p>

In this recording state, the modem (if so configured) monitors for line
silence. If the #VSP period expires, the modem sends
the &lt;DLE&gt;q or &lt;DLE&gt;s code to the DTE.</p><p>

Recording can be canceled only via two events:
</p><ol>
<li>The DTE sends any character to the modem. This is the key abort, and is
the normal method of terminating the receive mode.
</li><li>The S30 deadman timer expires, which is generally an undesired event.
</li></ol>


<table border="1">
<caption>Table 8-3.  Shielded DTE Codes</caption>

<tbody><tr><th>Code Sent to Modem
</th><th> Meaning

</th></tr><tr><td>&lt;DLE&gt;&lt;ETX&gt;
</td><td><b>Terminate</b>.
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. (This command is ignored by the modem when not in Voice
Transmit Mode.)

</td></tr><tr><td>&lt;DLE&gt;&lt;CAN&gt;
</td><td><b>Cancel</b>.
Sent during Voice Transmit Mode to indicate that the DTE 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. (This command
is ignored by the modem when not in Voice Transmit Mode.)

</td></tr><tr><td>&lt;DLE&gt;p
</td><td><b>Pause</b>.
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 (&lt;DLE&gt;r), or cancel &lt;DLE&gt;&lt;CAN&gt;, is received,
in which case the data is lost. If a &lt;DLE&gt;&lt;ETX&gt; 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 &lt;DLE&gt;&lt;ETX&gt;). 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.
(This command is ignored in other voice submodes.)

</td></tr><tr><td>&lt;DLE&gt;r
</td><td><b>Resume</b>.
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.

</td></tr></tbody></table>

<h4>8.2.7. Voice Playback</h4>

To effect playback of a message recorded via a handset or microphone,
or of a message recorded during a voice call, the DTE
must configure the modem for Voice Mode (#CLS=3D8) and select the proper
relay setup (#VLS) to instruct the modem whether to
use the handset or speaker. The modem responds to the #VLS command by
issuing a relay activate command to select the input
device. The hardware must provide a means of selecting a handset and/or
microphone instead of the telephone line, as this input
device. When a device other that the telephone line is selected, the modem
immediately enters Online Voice Command Mode (indicated
by VCON). DTMF detection is thus enabled as soon as the DTE selects the
device, such as a handset, although the user still
needs to physically pick up the telephone before he can issue DTMF tones.
Once selected, however, the user can indeed 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 exists but the DTE has not
yet commanded receive nor transmit.<p>

When the DTE decides to play the message, it issues the #VTX command, and
the modem immediately switches to Voice Transmit
Mode. Since the speaker or handset is already switched in, the modem
immediately issues the CONNECT message indicating that
the modem is in Voice Transmit Mode and is expecting voice data from
the DTE.</p><p>

A subsequent &lt;DLE&gt;&lt;ETX&gt; has to be issued to switch back to
Online Voice Command Mode.

</p><h4>8.2.8. Voice Call Termination</h4>

<h5>Local Disconnect</h5>

The DTE can disconnect from a telephone call by commanding a mode change to
 Online Voice Command Mode (if not already in it),
and by issuing the H command.

<h5>Remote Disconnect Detection</h5>

When in Voice Receive Mode, the modem sends the proper shielded &lt;DLE&gt;
code when loop break, dial tone, or busy tone is detected.
The modem stays in Voice Receive Mode, however, until the DTE issues a key
abort to force Online Voice Command Mode. The DTE
must issue the H command if it wishes to hang up.


<h4>8.2.9. Mode Switching</h4>

<h5>Voice to Fax</h5>

If the modem is in Online Voice Command Mode (i.e., it has gone off-hook
with #CLS=8 in effect), the DTE can attempt a fax
handshake by setting #CLS=1 or #CLS=2, followed by the A or D command
corresponding to fax receive or send. This has the effect
of beginning a fax Class 1 or Class 2 handshake (see #CLS command).

<h5>Unsuccessful Fax Connection Attempt to Voice</h5>

A fax handshake which does not succeed, attempted as the result of the DTE
modifying the #CLS setting from voice (8) to fax
(1 or 2), does not result in the modem hanging up, allowing the DTE the
flexibility of commanding a switch back to Voice Mode
with #CLS=8.

<h5>Voice to Data</h5>

If the modem is in the Online Voice Command Mode, the DTE can attempt a
data handshake by setting #CLS=0 followed by the A
or D command. This has the effect of beginning a Data Mode handshake
according to the current Data Mode S-register and command
settings.

<h5>Unsuccessful Data Connection Attempt to Voice</h5>

A data handshake which does not succeed, attempted as the result of the DTE
modifying the #CLS setting from voice (8) to data
(0), does not result in the modem hanging up, allowing the DTE
the flexibility of commanding a switch back to Voice Mode with #CLS=8.

<h4>8.2.10. Caller ID</h4>

The modem supports Caller ID by passing the information received in
Bell 202 FSK format to the DTE after the first RING detect.
The modem supports both formatted and unformatted reporting of Caller ID
information received in ICLID (Incoming Call Line
ID) format as supported in certain areas of the U.S. and Canada.
The DTE enables this feature via the #CID command.

<h3>8.3. AT VOICE COMMAND SUMMARY</h3>

Table 8-4 provides a complete summary of the AT voice commands described in
 detail in Sections 8.3.1 and 8.3.2.

<h4>8.3.1. Global AT Command Set Extensions</h4>

The AT commands in the following section are global, meaning that they can
be issued in any appropriate mode (i.e., any #CLS setting).<p>

For consistency, the command set is divided into action commands
and parameters (non-action commands). Those commands which
are action commands (i.e., those which cause some change in the current
operating behavior of the modem) are identified as
such, and the remaining commands are parameters.

</p><h5>ATA - Answering in Voice</h5>

The answer action command works analogously to the way it works in Data and
 Fax Modes except for the following:

<ol>
<li> When configured for Voice Mode (#CLS=8), the modem enters Online Voice
 Command Mode immediately after going off-hook. When
the #CLS=3D8 command is issued, the modem can be programmed to look for
1100 and 1300 Hz calling tones (see #VTD), thus eliminating
the need to do so as part of A command processing. After the VCON message
is issued, the modem re-enters Online Voice Command
Mode while sending any incoming DTMF or Calling Tone indications to the DTE
 as described in Section 8.2.5.

</li><li> After answering in Voice Mode (#CLS=8), the DTE, as part of its call
discrimination processing, can decide to change the
#CLS setting to attempt receiving a fax in Class 1, or to make a data
connection. In such a case, the DTE commands the modem
to proceed with the data or fax handshake via the A command even though the
 modem is already off-hook.
</li></ol>