interpolation is enabled if silence delet ion was selected for voice
compression.
8.2. VOICE CAPABILITIES
8.2.1. Call Establishment - Originate
Directed Originate (Dial as a specific modem type) For most call
originations, it is known ahead of time what type of call is being
attempted, and it is acceptable to disconnect if the remote side of the
connection does not cooperate. In this case, the modem can be
configured ahead of time with the existing +FCLASS (and +FAA=0) or the
#CLS command to be a data, fax, or voice modem. For Data and Fax
Modes, the modem subsequently either succeeds with the desired type of
connection, or eventually hangs up. For the Voice Mode, the DTE has
the option of hanging up if there are indications that the remote
station has not answered in voice, thus implementing a directed
originate for voice. The following are the three connection type
choices: Voice The modem dials and reports call progress to the DTE,
which reduces to reporting "NO DIALTONE," or "BUSY." The modem allows
the DTE to program a time period, which if elapsed after any ringback
is detected, forces the modem to assume the remote has gone off-hook.
A secondary time period (safety valve) can define a maximum elapsed
time after dialing for receiving no ringback before the modem assumes
that the remote has gone off-hook. This safety valve is devised in
case the remote picks up the telephone before any ringback is
generated, and no other tones are detected. In this mode, the modem is
attempting to make a voice connection only and therefore, while
waiting for ringback to disappear, it is also feasible to disconnect
upon detection something which is definitely not voice from the remote,
such as any answer tone. The modem provides detection of "ringback
went away or never came". Fax The modem dials and reports call
progress to the DTE as in all modes. A fax Class 1 or Class 2
handshake is pursued according to the current configuration. Data The
modem dials and reports call progress to the DTE as in all modes. A
data handshake is pursued according to the current configuration.
Adaptive Originate (Dial with Voice/Data/Fax Discrimination) The DTE
may wish to originate a call which adapts to the remote answerer. For
instance, the user may wish to send a voice message if a human picks up
the telephone, but a facsimile if a fax machine answers. The modem can
facilitate this type of adaptive originate by extending what it does
for the directed originate modes. After determining that the remote
station has picked up the line, the modem goes back to Online Voice
Command Mode, thus terminating the "connecting state." Once in this
mode, the modem reports what it receives from the answerer via specific
result codes to the DTE. The DTE can then have the option of pursuing
a data, fax, or voice connection.
8.2.2. Call Establishment - Answer
Directed Answer (Answer as a specific modem type) If the DTE wants to
be only one kind of answerer (i.e., voice, fax, or data), it can
configure the modem to answer exclusively in the chosen mode. Voice
The modem is configured to answer in Voice Mode only and assumes the
caller will cooperate. After going off-hook, the voice VCON is issued,
no answer tone is generated, and the modem is immediately placed in
Online Voice Command Mode. The DTE typically responds by sending a
greeting message of some type, and DTMF tone recognition/reporting can
be enabled. Eventually, an incoming voice message can be recorded by
the host. (Unpredictable results occur if the caller is not prepared
for a voice call.) Fax The modem is configured to answer in Class 1 or
Class 2 Fax Mode only, and it assumes the caller is going to cooperate.
This configuration has the effect of disabling Voice Mode, forcing
+FCLASS to either 1 or 2, and forcing both +FAA and +FAE to 0. Data
The modem is configured to answer in Data Mode only and assumes the
caller is going to cooperate. This configuration has the effect of
disabling Voice Mode, forcing +FCLASS = 0, and forcing both +FAA and
+FAE to 0. Adaptive Answer (Answer with Voice/Data/Fax Discrimination)
In normal operation, it is desirable for a modem supporting fax and
voice to provide the ability to discriminate between the two when
answering unsolicited or unattended calls. (It is most often the case
that a fax is received or a voice message recorded when nobody is
present.) Data/Fax Discrimination If the DTE wishes to allow for a data
or fax call, the +FCLASS and +FAA or +FAE commands can be configured
for adaptive answer between data and Class 1 or Class 2 fax. Voice/Fax
Discrimination This is the most important discrimination capability
needed from the user's standpoint. The modem must be configured for
Voice (#CLS=8), causing the modem to enter Online Voice Command Mode
immediately upon going off-hook. In Voice Mode, the DTE automatically
receives indications of DTMF tones and Calling Tones. The DTE can now
switch to Voice Transmit Mode in order to play a greeting message,
perhaps one which instructs the caller how to enter specific DTMF
sequences to switch modes. The DTE can then react to the response, or
the lack thereof, to such a message. The modem supports switching to a
Class 1 or Class 2 answer mode by virtue of the #CLS=1 or 2 commands,
and if such a switch is made and fails, the modem reports the failure
but does not hang up, allowing the DTE further experimentation time.
If the user wishes to switch to Class 1 or 2, but also wants the DTE to
indeed hang up the line if the fax fails, the +FCLASS command should be
used instead of the #CLS command. The only difference between these
commands is that issuing +FCLASS cancels the modem's memory of voice,
whereas #CLS causes the modem to remain off-hook, even if a fax or data
handshake fails, until it receives an H command. Voice/Data/Fax
Discrimination The DTE can try data modem operation after an answer by
changing the #CLS setting to 0. A data handshake attempt can be added
based upon DTMF responses or lack thereof.
8.2.3. Voice Data Transfer
A significant area of concern when handling the transfer of voice
data is the data transfer rate on the modem/DTE interface. Data
transfer rates can be expressed as the number of interrupts which must
be serviced per time period to keep up. This is a function of the
sampling rate and compression method (if any) used by the modem, and
the DTE interface speed required to handle the data flow on the
telephone line side. Table 8-1 demonstrates the relationship between
the sampling rate, interrupt rate, and DTE speed necessary for the
modem to support various compression ratios. The 16C550 UART is
strongly recommended to support Voice Mode operation, and is essential
for M S Windows environments.
Table 8-1. 7.2 KHZ Sample Rate DTE Speeds
Modem Samples per 8-bit Byte
Required Asynchronous DTE Speed (8N1 Format)
Implied DTE Speed Supported
2 (4-bits)
36,000 bps
38.4 kbps
2.66 (3-bits)
27,000 bps
38.4 kbps
4 (2-bits)
18,000 bps
19.2 kbps
Note: The current exclusive sampling rate is 7.2 kHz.
8.2.4. Tone and Status Monitoring_ Shielded <DLE> Statuses
The modem can detect specific tones and other status information, and
report these to the DTE while in any of the three voice submodes. The
modem simultaneously looks for 1300 and 1100 Hz calling tones when
answering, and for CCITT and Bell answer tones when originating. The
modem can also detect dial or busy tones in any of the three voice
submodes. All detected tones, as well as certain other statuses
addressed in Table 8-2 such as silence and "telset off-hook" (i.e.,
handset off-hook) are reported as shielded codes. When in Online
Voice Command Mode or Voice Transmit Mode, the codes in Table 8-2 are
sent to the DTE immediately upon verification by the modem of the
associated tone, status, or cadence. In this mode, the 2-character
code is not buffered, nor does the DTE have the ability to stop the
code with flow control. If the DTE has started (but not completed)
sending any AT command, the Tone Monitoring function is disabled until
the command has been received and processed. The modem can
discriminate between single and multiple DTMF tones received. If
calling tone, dial tone, busy tone, or answer tone is detected, this
detection is reported repeatedly (at reasonable intervals) if the DTE
takes no action, and the tone continues to be detected.
Table 8-2. Shielded Codes Sent to the DTE
Code Sent to DTE
Meaning
<DLE>0 - <DLE>9, <DLE>*, <DLE>#, <DLE>A -<DLE>D
DTMF. Digits 0 through 9, *, #, or A through D detected by the
modem, i.e., user has pressed a key on a local or remote telephone.
The modem sends only one <DLE> code per DTMF button pushed.
<DLE>a
Answer Tone (CCITT). Send to the DTE when the V.25/T.30 2100 Hz
Answer Tone (Data or Fax) 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 once every half second.
<DLE>b
Busy. Sent in Voice Receive Mode when the busy cadence is detected,
after any remaining data in the voice receive buffer. The modem sends
the busy <DLE>b code every 4 seconds if busy continues to be detected
and the DTE does not react. This allows the DTE the flexibility of
ignoring what could be a false busy detection.
<DLE>c
Calling Tone. Sent when the T.30 1100 Hz Calling Tone (Fax Modem) is
detected in any of the voice operating modes. 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
<DLE>c, and calling tone continues, the code is sent again as often as
once every 4 seconds.
<DLE>d
Dialtone. Sent in Voice Receive Mode when dial tone is detected
after any remaining data in the voice receive buffer. The modem sends
the <DLE>j 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.
<DLE>e
European Data Modem Calling Tone. 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 <DLE>e and calling tone continues, the code is sent again
as often as once every 4 seconds.
<DLE>f
Bell Answer Tone. 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.
<DLE>h
Hung Up Handset. 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.
<DLE>o
Overrun. 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 t he <DLE>o at the end of the
buffer, thus marking the location where data was lost by the DTE. The
modem does not append<E> <D><DLE>o codes to the buffer contiguously.
If more than one data byte is lost before the DTE begins reading again,
there is only on <DLE>o code in the data stream. However, if the DTE
resumes reading, and then once again allows the buffer to overflow, a
new <DLE>o is appended to the data by the modem. Thus, the<E>
<D><DLE>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.
<DLE>q
Quiet. 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, <DLE>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
<DLE>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.
Table 8-2. Shielded Codes Sent to the DTE (Cont'd)
Code Sent to DTE
Meaning
<DLE>s
Silence. Sent in Voice Receive Mode after the silence detection
timer (#VSP) expires and if valid voice has not been detected (#VSS).
In general, <DLE>s is sent if no sound was detected at all. This
differs slightly from Quiet (<DLE>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
<DLE>s code, the modem automatically resets its timer and sends the
code again if the #VSP time period a gain expires. This allows the DTE
time to react to what may be a false detection of silence.
<DLE>t
Handset Off-Hook. Sent one time when the local handset transition
from on-hook to off-hook is detected in any of the three voice
submodes.
<DLE>u
Underrun. Sent in Voice Transmit Mode when the voice transmit buffer
becomes empty without receiving a <DLE><ETX> or <DLE><CAN> command
first. The modem remains in transmit mode, but issues the <DLE>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.
<DLE><ETX>
End of Stream. <DLE><ETX> 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.
8.2.5. Shielded <DLE> Commands from the DTE
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
<DLE><ETX> which the DTE issues during Voice Transmit Mode to terminate
an output message. Table 8-3 lists shielded <DLE> commands recognized
by the modem.
8.2.6. Voice Record
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. 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>q or <DLE>s code to the DTE.
Recording can be canceled only via two events:
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, which is generally an undesired
event.
Table 8-3. Shielded DTE Codes
Code Sent to Modem
Meaning
<DLE><ETX>
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. (This command is ignored by the modem when not in Voice Transmit
Mode.)
<DLE><CAN>
Cancel. 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.)
<DLE>p
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.
(This command is ignored in other voice submodes.)
<DLE>r
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.
8.2.7. Voice Playback
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=8) 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 delive red via shielded
codes, identically to when a physical telephone connection exists but
the DTE has not yet commanded receive nor transmit. 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. A subsequent <DLE><ETX> has
to be issued to switch back to Online Voice Command Mode.
8.2.8. Voice Call Termination
Local Disconnect
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. Remote Disconnect Detection When in Voice
Receive Mode, the modem sends the proper shielded <DLE> 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.
8.2.9. Mode Switching
Voice to Fax
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). Unsuccessful Fax Connection
Attempt to Voice 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.
Voice to Data 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.
Unsuccessful Data Connection Attempt to Voice 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 #CL S=8.
8.2.10. Caller ID
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.
8.3. AT VOICE COMMAND SUMMARY
Table 8-4 provides a complete summary of the AT voice commands
described in detail in Sections 8.3.1 and 8.3.2.
8.3.1. Global AT Command Set Extensions
The AT commands in the following section are global, meaning that
they can be issued in any appropriate mode (i.e., any #CLS setting).
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.
ATA - Answering in Voice
The answer action command works analogously to the way it works in
Data and Fax Modes except for the following:
1. When configured for Voice Mode (#CLS=8), the modem enters Online
Voice Command Mode immediately after going off-hook. When the
#CLS=8 command is issued, the modem can be programmed to look
for 1100 and 1300 Hz calling tones (see #VTD), thus eliminatng 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.
2. 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.
Result Code:
VCON Issued in Voice Mode (#CLS=8) immediately after going off-hook.
Table 8-4. AT Voice Commands
Command
Function
A
Answering in Voice Mode.
D
Dial command in Voice Mode.
H
Hang up in Voice Mode.
Z
Reset from Voice Mode.
#BDR
Select baud rate (turn off autobaud).
#CID
Enable Caller ID detection and select reporting format.
#CLS
Select data, fax, or voice.
#MDL?
Identify model.
#MFR?
Identify manufacturer.
#REV?
Identify revision level.
#VBQ?
Query buffer size.
#VBS
Bits per sample (ADPCM).
#VBT
Beep tone timer.
#VCI?
Identify compression method (ADPCM).
#VLS
Voice line select (ADPCM).
#VRA
Ringback goes away timer (originate).
#VRN
Ringback never came timer (originate).
#VRX
Voice Receive Mode (ADPCM)
#VSD
Silence deletion tuner (voice receive, ADPCM).
#VSK
Buffer skid setting.
#VSP
Silence detection period (voice receive, ADPCM).
#VSR
Sampling rate selection (ADPCM).
#VTD
DTMF/tone reporting capability.
#VTX
Voice Transmit Mode (ADPCM).
ATD - Dial Command in Voice
The dial action command works analogously to the way it works in Data
or Fax modes. When in Voice Mode (#CLS=8):
1. The modem attempts to determine when the remote has picked up the
telephone line and once this determination has been made, the VCON
message is sent to the DTE. This determination is initially made based
upon ringback detection and disappearance. (Se e #VRA and #VRN
commands.)
2. Once connected in Voice Mode, the modem immediately enters the
command state and switches to Online Voice Command Mode which enables
unsolicited reporting of DTMF and answer tones to the DTE.
Parameters: Same as Data and Fax modes.
Result Codes:
VCON Issued in Voice Mode (#CLS=8) when the modem determines that the
remote modem or handset has gone off-hook, or when returning to the
Online Voice Command Mode. (See #VRA and #VRN.)
NO ANSWER Issued in Voice Mode (#CLS=8) when the modem determines
that the remote has not picked up the line before the S7 timer expires.
ATH - Hang Up in Voice
This command works the same as in Data and Fax modes by hanging up
(disconnecting) the telephone line. There are, however, some specific
considerations when in Voice Mode:
1. The H command forces #CLS=0, but does not destroy any of the
voice parameter settings such as #VBS, #VSP, etc. Therefore, if the
DTE wishes to issue an H command and then pursue another voice call, it
must issue a subsequent #CLS=8 command, but it ne edn't reestablish the
voice parameter settings again unless a change in the settings is
desired.
2. The #BDR setting is forced back to 0, re-enabling autobaud.
3. If the #VLS setting is set to select a device which is not, or
does not include the telephone line (such as a local handset or
microphone), the H command deselects this device and reselects the
normal default setting (#VLS =0). Normally, the DTE shou ld not issue
the H command while connected to a local device such as a handset,
because merely selecting this device results in VCON. The normal
sequence of terminating a session with such a device is to use the #VLS
command to select the telephone line, which by definition makes sure it
is on-hook.
Parameters: Same as Data and Fax modes.
Result Codes: Same as Data and Fax modes.
ATZ - Reset from Voice Mode
This command works the same as in Data and Fax modes. In addition,
the Z command resets all voice related parameters to default states,
forces the #BDR=0 condition (autobaud enabled), and forces the
telephone line to be selected with the handset on-hook. No voice
parameters are stored in NVRAM so the profile loaded does not affect
the voice aspects of this command.
Parameters: Same as Data and Fax modes.
Result Codes: Same as Data and Fax modes.
#BDR - Select Baud Rate (Turn off Autobaud)
This command forces the modem to select a specific DTE/modem baud
rate without further speed sensing on the interface. When a valid
#BDR=n command is entered, the OK result code is sent at the current
assumed speed. After the OK has been sent, the modem switches to the
speed indicated by the #BDR=n command it has just received. When in
Online Voice Command Mode and the #BDR setting is nonzero (no autobaud
selected), the modem supports a full duplex DTE interface. This means
that the DTE can enter commands at any time, even if the modem is in
the process of sending a shielded code indicating DTMF detection to
the DTE. When in Online Voice Command Mode and the #BDR setting is
zero (autobaud selected), shielded code reporting to the DTE is
disabled. [Note that when #BDR has been set nonzero, the modem employs
the S30 Deadman Timer, and this timer starts at the point where #BDR is
set nonzero. If this period expires (nominally 60 seconds) with no
activity on the DTE interface, the modem reverts to #BDR=0 and #CLS=0.]
Parameters: n = 0 - 48 (New baud rate is n*2400 bps)
Default: 0
Result Codes:
OK If n = 0 - 48.
ERROR Otherwise.
Command options:
#BDR? Returns the current setting of the #BDR command as an ASCII decimal value in result code format.
#BDR=? Returns a message indicating the speeds that are supported.
#BDR=0 Enables autobaud detection on the DTE interface.
#BDR=n Where 1<n<48. Sends OK message at current speed, then
switches to the new speed defined by n*2400 bps unless and until
another #BDR=n command is received. Autobaud is disabled, and
the character format is maintained at the format most recently
detected.
#CID - Enable Caller ID Detection and Select Reporting Format
This command selects or disables Caller ID recognition and reporting
in any mode.
Parameters: n = 0, 1, or 2
Default: 0
Result Codes:
OK n = 0, 1, or 2.
ERROR Otherwise.
Command options:
#CID? Returns the current setting (0,1 or 2) of the #CID command as
an ASCII decimal value in result code format.
#CID=? Returns the message, "0,1,2".
#CID=0 Disables Caller ID.
#CID=1 Enables formatted Caller ID reporting of ICLID SDM (Single Data
Message) and MDM (Multiple Data Message) packets.
#CID=2 Enables unformatted Caller ID reporting of any ICLID packet received
after the first RING cycle
including SDM, MDM, or call waiting packets.
#CLS - Select Data, Fax,
or Voice This command selects Data, Fax, or Voice Mode from operation
in any mode. Parameters: n = 0, 1, 2, or 8 Default: 0 Result Codes: OK
If n = 0, 1, 2, or 8. ERROR Otherwise. Command options:
#CLS? - Returns the current setting (0,1,2, or 8) of the #CLS command as an
ASCII decimal value in result code format. #CLS=? Returns the
message, "0,1,2,8".
#CLS=0 Data. This is similar to
setting +FCLASS=0, and instructs the modem to act like a data modem on
subsequent answer or originate operations. When a disconnect or
inactivity time out in the non-autobaud mode is detected, the modem
automatically sets the #CLS setting to 0 and hangs up. This ensures
that the modem is always in a known state despite disorderly DTE
behavior.
#CLS=1 Class 1 fax. This is similar to setting +FCLASS=1,
and instructs the modem to be a Class 1 fax modem. Once this is set,
either the +FAA or +FAE command can be used to force subsequent answers
to be Class 1 adaptive answers.
#CLS=2 Class 2 fax. This is similar to setting +FCLASS=2, and instructs the
modem to be a Class 2 fax modem. Once this is set, the +FAA command
can be used to force subsequent answers to be Class 2 adaptive answers.
#CLS=8 Voice Mode. This is the main setting the DTE uses to effect
directed or adaptive answer or originate sequences involving voice
modes. All telephone calls initialized by #CLS=8 result (after answer
or successful call progress) in the modem in Online Voice Command Mode.
#MDL? - Identify Model. This command requests the model number or name of
the modem. (The response returned may be altered by the OEM via the
ConfigurACE utility program.)
Command option:
#MDL? - RC96V24AC
#MFR? - Identify Manufacturer This command requests the modem manufacturer.
(The response returned may be altered by the OEM via the ConfigurACE
utility program.)
Command option:
#MFR? - ROCKWELL
#REV? - Identify Revision Level This command requests the revision level
of the modem. (The response returned may be altered by the OEM via
the ConfigurACE utility program.)
Command option:
#REV? - XXXX-XXXX-XXX YYY (Those places occupied by "X"'s represent the part number, while those places occupied by `Y"'s represent the revision number. The values are determined at time of production.)
8.3.2. AT#V Commands Enabled Only in Voice Mode (#CLS=8)
The commands described in the following subsection are extensions to
the command set which the modem recognizes only when configured for
Voice Mode with the #CLS=8 command.
#VBQ? - Query Buffer Size
This query-only command returns the size of the modem's voice
transmit and voice receive buffers in ASCII decimal, followed by the OK
result code.
Parameters: None
Command option:
#VBQ? Returns the size of the modem voice transmit and voice receive buffers.
#VBS - Bits Per Sample (Compression Factor)
This command selects the degree of ADPCM voice compression to be
used.
Parameters: n = 2, 3, or 4 (Voice compression bits per sample)
Default: 4
Result Codes:
OK If n = 2, 3, or 4.
ERROR Otherwise.
Command options:
#VBS? Returns the current setting of the #VBS command as an ASCII decimal
value in result code format.
#VBS=? Returns "2,3,4", which are the ADPCM compression bits/sample rates
available. These bits/sample rates are correlated with the #VCI?
query command response which provides the single compression method
available.
#VBS=2 Selects 2 bits per sample.
#VBS=3 Selects 3 bits per sample.
#VBS=4 Selects 4 bits per sample.
#VBT - Beep Tone Timer
This command defines the time period, in 10ths of a second up to 4
seconds (40) which is used by the modem as the DTMF or fixed tone
duration for generating tones via the D command while in Online Voice
Command Mode.
Parameters: n = 0 - 40 (0 - 4 seconds)
Default: 10
Result Codes:
OK If n = 0 - 40.
ERROR Otherwise.
Command options:
#VBT? Returns the current setting of the #VBT command as an ASCII
decimal value in result code format.
#VBT=? Returns the message, "0-40".
#VBT=0 Disables the tone generation capability.
#VBT=1 to 40 Sets tone duration time.
#VCI? - Identify Compression Method
This command queries the modem as to its compression method and raw
bits-per-sample capability. <OP0C0>;<D> pairs, separated by <LF0>s.
Within each line, the <O> is left justified, and is separated from the
<D> by the semicolon character and separated fro m the bits-per-sample
string by another semicolon.<F255P255C255>
Parameters: None
Command option:
#VCI? Returns the message, "ROCKWELL;ADPCM;8".
#VLS - Voice Line Select
This action command can be used to select which devices are routed
through the modem.
Parameters: n = 0, 1, 2, 3, or 4 [This is the device position number
(not device number) as reflected in response to #VLS=?]
Default: 0
Result Codes:
OK If n = 0, 1, 2, 3, or 4.
VCON If device selected does not connect to the telephone line. (A speaker
is such a device, but a telephone line with speaker ON is not such a
device, and generates OK.) ERROR If n does not equal 0, 1, 2, 3, or 4,
or if already off-hook.
Command options:
#VLS? This query returns the current setting of the #VLS command as an
ASCII decimal value in result code format.
#VLS=? This query requests a report of the device types available
for selection. The response is a series of numbers separated by
commas, and each number indicates a device position number. Currently,
device position numbers do happen to correspond to device type numbers
as shown in Table 8-5, but this correlation is not required (i.e., 0's
could be placed in the first few device position number locations to
correspond to multiple telephone line connections).
#VLS=0 The default option on the modem. This command instructs the
modem that when entering any of the three voice operating submodes
(Online Command, Transmit, or Receive), that the telephone line
interface should be routed through the modem. The OK response is sent
to the DTE, and any previous connection is lost (i.e., the modem ends
up on-hook as a result of issuing this command to connect to the
telephone line).
#VLS=1 This command instructs the modem to route only the handset through
the modem. This setting can be chosen before recording a greeting message.
#VLS=2 This command instructs the modem to route only the speaker
through the modem. This setting can be chosen before playing back any
message. The modem immediately switches to Online Voice Command Mode ,
and the VCON response is generated for completeness. However, since
this is an output only device, nothing of consequence can happen until
the DTE sends the #VTX command.
#VLS=3 This command instructs the modem that only the auxiliary input
device (microphone) should be routed through the modem. This setting
can be chosen before recording a greeting message.
#VLS=4 This command is the same as #VLS =0, except that the modem enables
the internal speaker as well as the telephone line/handset circuit.
Table 8-5. Device Types Supported by #VLS
ASCII Digit
Device Type and Considerations
0
Telephone Line with Telephone handset. This is the default device
selected. In this configuration, the user can pick up a handset which
is connected to the same telephone line as the modem, and * record both
sides of a conversation with a remote station. The modem currently
supports one telephone line/handset, which is in the first position of
the #VLS=? response. (Note that the modem can interface to multiple
telephone lines by having "0"'s in multiple positions in the #VLS ?
response.) If a telephone line is selected, the modem must be on-hook
or it hangs up. The OK message is generated.
1
Transmit/Receive Device (other than telephone line). This is a
handset, headset, or speaker-phone powered directly by the modem. When
such a device is selected, the modem immediately enters Online Voice
Command Mode, DTMF monitoring is enabled if applicable, and the VCON
response is sent. The modem supports one such device as the second
device listed in the #VLS=? response.
2
Transmit Only Device. Normally, this is the onboard speaker. When
this device is selected, the modem immediately enters Online Voice
Command Mode, and the VCON response is sent. The modem supports
selection of the internal speaker as the third device listed in
#VLS= ? response.
3
Receive Only Device. Normally, this is a microphone. When such a
device is selected, the modem immediately enters Online Voice Command
Mode, DTMF monitoring is enabled if applicable, and the VCON response
is sent. The modem supports one microphone as the fourth element
returned in the #VLS =? response.
4
Telephone line with Speaker ON and handset. This device type can be
used to allow the DTE to select the telephone line/handset (if picked
up) with the modem speaker also turned ON. This can be used by the DTE
to allow the user to monitor an incoming message as it is recorded.
#VRA - Ringback Goes Away Timer (Originate)
This command can be used, when originating a voice call (#CLS=8) to
set the "Ringback Goes Away" timer value, i.e., an amount of time (in
units of 100 ms) measured from when the ringback cadence stops once
detected. If ringback is not detected within this period, the modem
assumes that the remote has picked up the line and switches to Online
Voice Command Mode. Every time a ringback cycle is detected, this
timer is reset.
Parameters: n = 0 - 255 (0 - 2.55 seconds)
Default: 70
Result Code: OK
Result Code:
OK If n = 0 - 255.
ERROR Otherwise.
Command options:
#VRA? Returns the current setting of the #VRA command as an ASCII decimal
value in result code format.
#VRA=? Returns the message, "0-255".
#VRA=0 Turns off the "ringback goes away timer." After one ringback, the
dialing modem sends VCON and enters Online Voice Command Mode
immediately.
#VRA=n Where n defines the period without ringback (after at least one
ringback has been detected) in 100 ms units.
#VRN - Ringback Never Came Timer (Originate)
This command can be used when originating a voice call (#CLS=8) to
set the "Ringback Never Came" timer value, i.e., an amount of time (in
units of 100 ms) measured from completion of dialing. If ringback is
not detected within this period, the modem assumes the remote has
picked up the line and switches to Online Voice Command Mode.
Parameters: n = 0 - 255 (0 - 2.55 seconds)
Default: 100
Result Code:
OK If n = 0 - 255.
ERROR Otherwise.
Command options:
#VRN? Returns the current setting of the #VRN command as an ASCII decimal
value in result code format. #VRN=? Returns the message, "0-255".
#VRN=0 Turns off the "ringback never came timer." After dialing, the modem
sends VCON and immediately enters Online Voice Command Mode.
#VRN=n Where n defines the period without ringback after dialing in 100 ms
units.
#VRX - Voice Receive
This action command is only valid if the modem is in the Online Voice
Command Mode (indicated previously with the VCON message), and is the
switch to the Voice Receive Mode. This command is used when a voice
file is to be received from the line, microphon e, or handset. The
#VLS command should have been previously issued to select the input
source.
Parameters: None
Result Codes:
CONNECT When voice transfer from modem to DTE can begin.
ERROR If #VLS=0 and not connected to any input device.
#VSD - Enable Silence Deletion (Voice Receive)
This command is used to enable or disable Voice Receive Mode silence
deletion.
Parameters: n = 0 or1
Default: 0 or 1
Result Code:
OK If n = 1.
ERROR Otherwise.
Command options:
#VSD? Returns the current setting of the #VSD command as an ASCII decimal
value in result code format.
#VSD=? Returns the message, "1".
#VSD=0 Turns off the silence deletion.
#VSD=1 Turns on the silence deletion if the silence sensitivity setting
#VSS is nonzero. The aggressiveness of the silence deletion is
controlled by #VSS.
#VSK - Buffer Skid Setting
This command queries and sets the number of bytes of spare space,
after the XOFF threshold is reached, in the modem's buffer during Voice
Transmit Mode. This equates to the "skid" spare buffer space, or the
amount of data the DTE can continue to send after being told to stop
sending data by the modem, before the modem voice transmit buffer
overflows.
Parameter: n = 255 (Number of bytes of "skid spare buffer space)
Default: 255
Result Code:
OK If n = 255.
ERROR Otherwise.
Command options:
#VSK? Returns the current setting of the #VSK command as an ASCII decimal value in result code format.
#VSK=? Returns the message, "255".
#VSK=n n defines the 255 unused bytes remaining in the modem voice transmit buffer after an XOFF is sent to the DTE.
#VSP - Silence Detection Period (Voice Receive)
This command sets the Voice Receive Mode silence detection period
(inactivity timer) value. The parameter, in units of 100 ms, can be
used when receiving voice data. This is an amount of time, which if
elapsed without receiving any ADPCM data, causes the modem to send the
<DLE>s or <DLE>q codes after insuring that the buffer is empty. There
are two cases:
1. With the modem's silence deletion feature enabled, the #VSP
setting is in effect an inactivity timer. The modem must reset this
timer on every byte of voice data received.
2. With the modem's silence deletion feature disabled, the modem
determines what constitutes silence. This involves monitoring and
debouncing the modem value for average energy. If this debounced value
is less than an arbitrary threshold constituting the modem's
definition of silence for a period greater than that defined by the
#VSP setting, the modem sends the <DLE>q or <DLE>s shielded code to the
DTE.
Parameters: n = 0 - 255 (0 - 25.5 seconds)
Default: 55
Result Code:
OK If n = 0 - 255.
ERROR Otherwise.
Command options:
#VSP? Returns the current setting of the #VSP command as an ASCII decimal
value in result code format. #VSP=? Returns the message, "0-255".
#VSP=0 Turns off the silence period detection timer.
#VSP=n Where n defines the period without received voice data in 100 ms units.
#VSR - Sampling Rate Selection
This parameter, along with the bits per sample (#VBS) command,
determines the necessary DTE interface speed to transmit and receive in
the Voice Mode.
Parameter: n = 7200 (7200 Hz sampling rate)
Default: 7200
Result Codes:
OK If n = 7200.
ERROR Otherwise.
Command options:
#VSR? Returns the current setting of the #VSR command as an ASCII decimal
value in result code format.
#VSR=? Returns the message, "7200".
#VSR=7200 Default.
#VSS - Silence Detection Tuner (Voice Receive)
This command enables or disables the Voice Receive mode silence
detection, and controls the sensitivity employed by the modem in
compressing periods of silence.
Parameters: n = 0 - 3
Default: 2
Result Codes:
OK If n = 0 - 3.
ERROR Otherwise.
Command options:
#VSS? Returns the current setting of the #VSS command as an ASCII decimal
value in result code format.
#VSS=? Returns the message, "0-3".
#VSS=0 Disables silence detection by the modem when in Voice Receive Mode.
#VSS=1 Least sensitive setting. When this command is received by the
modem, the system is configured to a state which is least likely to
detect and compress periods of silence, but still able to do so if the
line is really quiet.
#VS=2 Midrange setting (default). When this command is received by
the modem, the system is configured to a state which is likely to be
the best overall compromise on normal telephone lines.
#VSS=3 Most sensitive setting. When this command is received by the
modem, the system is configured to a state which is most likely to
detect and compress periods of silence.
#VTD - DTMF Tone Reporting
This command queries and controls which types of tones can be
detected and reported to the DTE via shielded codes in Voice Transmit,
Voice Receive, and Online Voice Command Modes.
Parameters: i,j,k (three ASCII hexadecimal bit maps)
Default: 3F,3F,3F
Result Codes:
OK If bits supported with #VTD=? are selected.
ERROR Otherwise.
Command options:
VTD? Returns the current setting of the #VTD command as an ASCII decimal
value in result code format.
#VTD=? Returns the tone reporting capabilities of the modem.
#VTD=i,j,k Where i,j,k corresponds (in ASCII hexadecimal) to the desired
capabilities, as shown in Table 8-6, for Voice Transmit, Voice
Receive, and Online Voice Command Modes, respectively.
Table 8-6. #VTD Tone Detection/Reporting Bit Settings
Bit | Description
--- | -----------
0
0 = Disable DTMF tone capability;
1 = Enable DTMF tone capability 1.
1
0 = Disable V.25 1300 Hz Calling tone capability;
1 = Enable V.25 1300 Hz Calling tone capability 1.
2
0 = Disable T.30 1100 Hz Facsimile Calling tone capability;
