.....#V Command.....
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.
The answer action command works analogously to the way it
works in Data and Fax Modes except for the following:
- 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 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.
- Speakerphone
-
- If in Speakerphone mode (#VLS=6),
Speakerphone operation starts immediately after
going off-hook. No DTMF or Calling Tones can be
detected.
- An explicit ATA is required to actuate
speakerphone operation regardless of the current
hook or line status.
- 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.
The dial action command works analogously to the way it works
in Data or Fax modes. When in Voice Mode (#CLS=8):
- 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. (See #VRA
and #VRN
commands.)
- 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.
- If in Speaker Phone mode (#VLS=6), speaker phone
operation starts immediately after the ATD command is
issued.
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.
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:
- 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 needn't reestablish the
voice parameter settings again unless a change in the
settings is desired.
- The #BDR
setting is forced back to 0, re-enabling autobaud.
- 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
re-selects the normal default setting (#VLS =0).
Normally, the DTE should 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.
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 (#VLS=0). 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.
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.
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)
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.
This command selects or disables Caller ID recognition and
reporting in any mode.
Parameters:
n = 0, 1, or 2
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.
This command selects Data, Fax, or Voice Mode from operation
Parameters:
n = 0, 1, 2, or 8
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 available for compatibility
purposes. The result of this command is similar to
setting +FCLASS=2.0 and instructs the modem to be a Class
2.0 fax modem. Once this is set, the +FAA command can be
used to force subsequent answers to be Class 2.0 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.
This command requests the model number or name of the modem.
Command option:
- #MDL?
- USRobotics144FX
- USRobotics336FX
This command requests the modem manufacturer.
Command option:
- #MFR?
- USRobotics
This command requests the revision level of the modem. The
response to this command is the modem's serial number which
includes product code and hardware revision level.
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.)
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.
When USRobotics GSM voice compression is in use, this command
has no effect. When ADPCM voice compression is in use, this
command selects the degree of compression to be used. This
setting defines the number of bits per sample.
Parameters:
- n = 2, 3, or 4
Result Codes:
- OK
- If n = 2, 3, or 4
- ERROR
- Otherwise.
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 = 10, 0 - 40 (0 - 4 seconds)
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 - 40
- Sets tone duration time.
This command queries the modem as to the available compression
methods and raw bits-per-sample capability. The response is in
the form of "<author;method;bps>".
Parameters:
- None
Command option:
- #VCI?
- USRobotics;GSM;8
USRobotics;ADPCM;4
This command sets the speaker volume in speaker phone mode.
Parameters:
n = 0 - 255 (128)
Based on this parameter, the threshold for the Automatic Gain
Control (AGC) is set inside the DCE. The number otherwise has no
meaning. The value of zero mutes the speaker. Values larger than
128 indicate a larger gain than nominal and values less than 128
indicate smaller gain than nominal.
This command sets the sensitivity of the microphone in speaker
phone mode.
Parameters:
n = 0 - 255 (128)
Based on this parameter, the threshold for the Automatic Gain
Control (AGC) is set inside the DCE. The number otherwise has no
meaning. The value of zero mutes the microphone. Values larger
than 128 indicate a larger gain than nominal and values less than
128 indicate smaller gain than nominal.
This action command can be used to select which devices are
routed through the modem.
Parameters:
n = 0, 1, 2, 3, 4 or 6
This is the device position number (not device number) as
reflected in response to #VLS=?
Result Codes:
- OK
- If n = 0, 1, 2, 3, 4 or 6.
- 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, 4 or 6, 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,
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
#VTXcommand.
- #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. However, since this is an input only
device, nothing of consequence can happen until the DTE
sends the #VRX
command
- #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.
- #VLS=6
Available in the Sportster Voice modem only!
- This command instructs the modem that both the microphone
and speaker should be routed through the modem. This
setting is required for full duplex AEC speaker phone
operation.
This command can be used, when originating a voice call
(#CLS=8) to set the "Ringback Goes Away" timer value
measured in units of 100ms. (i.e. an amount of time 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.
If in Speaker Phone mode (#VLS=6), the modem will detect
ringback, busy, and dial tone.
Parameters:
n = 0 - 255 (0 - 2.55 seconds)
Default:
70
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 100ms units.
This command can be used, when originating a voice call
(#CLS=8) to set the "Ringback Never Came" timer value
measured in units of 100ms. (i.e. an amount of time measured from
completion of dialing. 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.
If in Speaker Phone mode (#VLS=6), the modem will detect
ringback, busy, and dial tone.
Parameters:
n = 0 - 255 (0 - 2.55 seconds)
Default:
70
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.
- #VRA=?
- Returns the message "0-255".
- #VRA=0
- Turns off the "ringback never came" timer.
After dialing the modem sends VCON and enters Online
Voice Command mode immediately.
- #VRA=n
- Where n defines the period without ringback after dialing
in 100ms units.
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 data is to be received from input
device selected by the #VLS command.
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 or
#VLS=6.
This command is used to enable or disable Voice Receive Mode
silence deletion.
Parameters:
n = 0 or 1
Result Codes:
- OK
- If n = 0 or 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
- Disables silence deletion.
- #VSD=1
- Enables silence deletion if the silence sensitivity
setting (#VSS) is non-zero. The aggressiveness of the
silence deletion is controlled by #VSS.
This command selects the method of compression and the
sampling rate. The format of the command is
#VSM=<cml>,<vsr>.
<cml> : DTE uses this parameter to select the
compression method. This subparameter is the means to select the
compression method, and has the form of a numerical constant. The
DTE can obtain the label and an identifier using the #VSM=?
command.
<vsr> : The DTE selects the DCE Voice sampling rate from
among those supported; listed in the response of the #VSM=?
command. The units are samples for second. This value overwrites
the #VSR command.
#VSM=?
The response for this command will be
<cml>,<cmid>,<vsr>
<cr><lf><cml><cr><lf>
<cml> : this sub parameter is a numerical label of the
compression method.
<cmid> : This sub parmeter is a string describing the
Compression method.
<vsr> : This sub parameter is a range of values that
contains the DCE supported range of voice samples per second of
the analog signal.
eg. #VSM=?
128,"GSM/USR",8000
129,"ADPCM/USR",8000
#VSM?
The response for this command should be the current
compression method and the sampling rate.
eg., 128,8000
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 voice data, causes
the modem to send the <DLE>s or <DLE>q codes after
insuring that the buffer is empty. There are two cases:
- 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.
- With the modem's silence deletion feature disabled, the
modem determines what constitutes silence. This involves
monitoring and de-bouncing the modem value for average
energy. If this de-bounced 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 = 55, 0 - 255 (0 - 25.5 seconds)
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.
This parameter, along with the bits per sample
(#VBS)
command, determines the necessary DTE interface speed to transmit
and receive in the Voice Mode. The sampling rate is in hertz.
Parameter:
- n = 8000
Result Codes:
- OK
- If n = 8000.
- 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, "8000".
- #VSR=8000
- Default.
This command enables or disables the Voice Recieve mode
silence detection and controls the sensitivity employed by the
modem in compressing periods of silence.
Parameters:
- n=0, 1, 2,3
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 the 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.
- #VSS=2
- Midrange setting (default). When this command is received
by the modem the system is configured to a state which is
most 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.
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 2-1, for Voice
Transmit, Voice Receive, and Online Voice Command Modes,
respectively.
Table 2-1. #VTD Tone Detection/Reporting
Bit Settings
|
Bit
|
Decimal
|
Description
|
|
0
|
1
|
0 = Disable DTMF tone capability
|
|
|
1 = Enable DTMF tone capability
|
|
1
|
2
|
0 = Disable V.25 1300 Hz Calling tone
capability
|
|
|
1 = Enable V.25 1300 Hz Calling tone
capability
|
|
2
|
4
|
0 = Disable T.30 1100 Hz Facsimile
Calling tone capability
|
|
|
1 = Enable T.30 1100 Hz Facsimile
Calling tone capability
|
|
3
|
8
|
0 = Disable V.25/T.30 2100 Hz Answer
tone capability
|
|
|
1 = Enable V.25/T.30 2100 Hz Answer
tone capability
|
|
4
|
16
|
0 = Disable Bell 2225 Hz Answer tone
capability
|
|
|
1 = Enable Bell 2225 Hz Answer tone
capability
|
|
5
|
32
|
0 = Disable call progress tone and
cadence (e.g., busy and dial tone) capability
|
|
|
1 = Enable call progress tone and
cadence (e.g., busy and dial tone) capability
|
|
6
|
64
|
Reserved
|
|
7
|
128
|
Reserved
|
This action command can be issued to play one of more DTMF or
other tones (such as a "beep") if and only if the modem
is in the Online Voice Command Mode. The modem parses and plays
the tones defined in the parameter in the order listed, and no
key abort is accepted. The parameter can have three types of
elements separated by commas:
- Dual or Single Tones
- These are represented by a substring enclosed in square
brackets ("[ ]") within the parameter. Each
such substring consists of three sub-elements
corresponding to 2 frequencies in Hz (0, or 200-3000) and
a duration (ASCII decimal in units of 100 ms).
- Varying DTMF Digits
- This is represented by a substring enclosed in curly
braces ("{ }") within the parameter. Each such
substring consists of two sub-elements corresponding to a
DTMF digits (0-9,A-D,*,#), and alternate durations in
units of 100 ms.
Parameters:
The tone generation consists of elements in a list with each
element separated by commas.
Result Codes:
- OK
- Command to play tones on currently selected device is
accepted.
- ERROR
- Command was not issued during Online Voice Command Mode
or string is grammatically incorrect.
This action command can be issued if and only if the modem is
in the Online Voice command Mode (indicated previously with the
VCON message), and is the switch to Voice Transmit Mode. #VTX is
used when a voice file is to be transmitted to the line, speaker
, or handset. The #VLS
command should have
been previously issued to select the output source.
Parameters:
- None
Result Codes:
- CONNECT
- When voice transmission by DTE can begin.
- ERROR
- If #VLS =0 and output device not connected.
- <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>b
- Busy. Sent in Voice Command Mode when a busy signal is
detected after dialing.
- <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>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.
- <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 #VS P and #VSS settings, is probabl y not going to
start again. If the DTE ignores the & lt;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.
- <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. T his 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 t he #VSP time period a gain expires. This allows the
DTE time to react to what may be a false detection of
silence.
- <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.
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 3-2 lists shielded <DLE> commands recognized by the
modem.
- <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.)
S Registers
This S-register is global, meaning that it can be set in any
appropriate mode (i.e., any #CLS setting).
Range:
- n = 0 - 255
Command options:
- S30=0
- Deadman timer off. No matter how long it might continue,
the modem never spontaneously hangs up the telephone line
or switches to autobaud mode as a result of inactivity.
- S30=1 to 255
- This is the period of time (in seconds), which if expired
causes the modem to hang up the telephone line if it is
off-hook and no data has passed during the period. The
timer is also active whenever the #BDR setting is
non-zero. In order to avoid a state where speed sense is
disabled (even though the PC can crash, come back up, and
try to issue commands at what should be a supported
speed), the inactivity time-out occurs if there is no
data passed on the DTE interface within the S30 period,
even if the modem is on-hook. DTE software must not
select a nonzero setting for #BDR until it is ready to
establish a telephone call or virtual connection to a
speaker or microphone. When there is an inactivity time
out with #CLS=8, the modem always forces #CLS=0 and
#BDR=0.
This S-register is global, meaning that it can be set in any
appropriate mode (i.e., any #CLS setting).
Range:
n = 50, 0 - 255
Command options:
Linear scale determining the volume output from the DSP to AIC
to the world.
VCON is sent when the modem is configured for voice (#CLS=8),
or when after answering or originating a call, the modem enters
the Online Voice Command Mode for the first time. Typically, this
is immediately after an off-hook in answer mode, and after
ringback ceases in originate mode. VCON is also sent when the DTE
requests a switch from Voice Transmit Mode to Online Voice
Command Mode by issuing a <DLE><ETX> to the modem, or
when the DTE requests a switch from Voice Receive Mode to Online
Voice Command Mode via the key abort.
CONNECT is sent when switching from the Online Voice Command
Mode to either Voice Receive Mode via the #VRX command, or to
Voice Transmit Mode via the #VTX command. This message is sent to
the DTE to inform it that it may begin receiving or sending GSM
data.