Voice Commands

The AT voice command set follows ITU-T Recommendation V.253. The commands are sent through the com port, but the data path is sent either through the com port or through a DMA channel using the wave driver.

S32=<value> - Synthetic Ring Volume

S32 specifies the synthetic ring volume. It provides a synthetic ring volume in dB with an implied minus sign. The default is 10.

Range: 0 - 255.

S33=<value> - Synthesized Ring Frequency

This register specifies a synthetic ring frequency. Register values from one to five select a unique ring frequency.

Range: 0 - 5.

+FCLASS=8 - Enter Voice Mode

The command +FCLASS=8 (+FCLASS=<value> - Service Class Indication) puts the modem in voice mode. Speakerphone and TAD modes are subsumed under the more general heading of voice mode, and use a particular subset of voice mode commands to implement their respective features and functions.

The modem controller maintains the overall state of the system so as to know when voice commands are issued in the context of using the speakerphone versus TAD or other voice contexts.

+VCID=<pmode> - Caller-ID

Use this command to enable or to disable caller-ID. Result codes:

Table 171. +VCID Commands

Command Function
+VCID=0 Disables caller-ID (default).
+VCID=1 Enables formatted caller report.
+VCID=2 Enables unformatted caller report.

Table 172. +VCID Extended Syntax Commands

Command Function
+VCID=<pmode> Sets the status of caller-ID.
+VCID? Returns the current caller-ID pmode.
+VCID=? Queries the DCE for the range of supported caller-ID report formats. The DCE returns 0, 1, 2.

+VDR=<enable>,<report> - Distinctive Ringing and Cadence Report

Use this command to enable or disable the distinctive ringing feature. Distinctive ringing features are identified by the DROF=<length of ring in 0.1 s increments> and DRON=<length of silence in 0.1 s increments> result codes. The default value assigned to the <enable> and <report> parameters is zero.

Result codes:

Table 173. +VDR Commands

<enable> <report> Function

0

0 - 255

Disables the ring report result code.

1

0 - 255

Enables the ring report result code and sets the report delay to <report>/10. The result is evaluated in seconds.

Table 174. +VDR Extended Syntax Commands

Command Function
+VDR=<enable>,<report> Enables or disables distinctive ringing features.
+VDR? Returns the current values of <enable> and <report>.
+VDR=? Queries the DCE for the range of supported distinctive ring configurations. The DCE returns (0, 1), (0 - 255).

+VEM=<mask> - Event Reporting and Masking

The DTE can use this command to disable an event report regardless of the DCE state or of the analog signal source or destination configuration. <mask> is bits 0-33 (i.e., FFFFFFFFC). See the IS-101 specification for defined bit values.

Table 175. +VEM Extended Syntax Commands

Command Function
+VEM=<mask> Sets event reporting mask.
+VEM? Returns the current values of the <mask>.
+VEM=? Queries the DCE for the range of supported service level events.

+VGM=<gain> - Microphone Gain

Use this command to set the microphone gain of the speakerphone function. <gain> is an unsigned octet where values greater than 128 indicate a gain larger than nominal, and values smaller than 128 indicate a gain smaller than nominal. The gain control has a range between 0 and 255.

Result codes:

Table 176. +VGM Extended Syntax Commands

Command Function
+VGM=<gain> Sets the microphone gain level.
+VGM? Displays the current gain level.
+VGM=? Displays the supported speaker gain levels for the product.

+VGR=<gain> - Receive Gain Selection

Use this command to set the receive microphone gain control. The receive gain has a range of 0 - 255. However, the values are only significant between 121 and 134. Any value set below 121 uses the same gain as 121. And any value set above 134 uses the same gain as 134.
Note: While in TAD mode, this command may be used in TAD local recording to control the recording level from the microphone. While in speakerphone mode, this command controls the gain to the remote caller.

Result codes:

Table 177. <gain> Values

Command Function
<gain> = 128 Nominal level for receive gain from microphone (default).
<gain> = a value greater than 128 Increases gain above nominal level.
<gain> = a value less than 128 Decreases gain below nominal level.

 Table 178. +VGR Extended Syntax Commands

Command Function
+VGR = <level> Sets the microphone receive gain.
+VGR? Displays the current value of receive gain.
+VGR=? Displays the range of supported gain values.

+VGS=<gain> - Speaker Gain

Use this command to set the speaker gain of the speakerphone function. <gain> is an unsigned octet where values greater than 128 indicate a gain larger than nominal, and values smaller than 128 indicate a gain smaller than nominal. The speaker gain control has a range from 0 to 255.

Result codes:

Table 179. +VGS Command <gain> Values

Command Function
<level>=128 Nominal volume level for speaker gain (default).
<level> = a value > 128 Increases volume above nominal level.
<level> = a value < 128 Decreases volume below nominal level.

Table 180. +VGS Extended Syntax Commands

Command Function
+VGS = <level> Sets the speaker gain.
+VGS? Displays the current value of the speaker gain.
+VGS=? Displays the range of supported gain values.

+VGT=<level> - Speaker Volume Control

Use this command to set the speaker volume control.

Result codes:

  1.  OK if <level> = 0 - 255.
  2.  ERROR if <level> ≠ 0 - 255.

Table 181. <level> Values

Command Function
<level>=128 Nominal volume level for sending to speaker (default).
<level> = a value > 128 Increases volume above nominal level.
<level> = a value < 128 Decreases volume below nominal level.

Table 182. +VGT Extended Syntax Commands

Command Function
+VGT=<level> Sets the speaker volume level.
+VGT? Displays the current setting for the speaker volume level.
+VGT=? Displays the support speaker volume level values.

+VIP - Initialize Voice Parameters

Use the +VIP command to reset all the voice parameters to their default values. The command has no effect on the +FCLASS setting.

+VIT=<timer> - DTE/DCE Inactivity Timer

Use this command to set the DTE/DCE inactivity timer. The DTE/DCE inactivity timer is activated when the DTE or host system selects voice fixed-rate mode. If the timer lapses, the DCE drops the connection. Inactivity in either the voice command mode or the voice data mode starts the countdown. The units are in one-second intervals.

Result codes:

Table 183. +VIT Extended Syntax Commands

Command Function
+VIT=<timer> Sets the DTE/DCE inactivity timer.
+VIT? Displays the current value of the timer.
+VIT=? Displays the range of supported delay times in seconds.

+VNH=<Hook> - Automatic Hang-Up Control

Use this command to enable or disable automatic DCE hang-ups in the data and facsimile modes. The +VNH command is part of a group of commands used for call discrimination. Call discrimination is a means for the modem to supply the DTE or host system with the information and means to discriminate between data, FAX, and voice calls. The automatic hang-up control is just one of the controls used to manage call discrimination. Refer to Section 5.3.1 of ITU-T Recommendation V.253 (02/98) for a full description of call discrimination and how the +VNH command is used.

Result codes:

Table 184. +VNH Commands

Command Function
+VNH = 0 The DCE retains automatic hang-ups (as in the other nonvoice modes).
+VNH = 2 The DCE disables automatic hang-ups in the other nonvoice modes. The DTE only performs a logical hang-up (returns the OK result code).

Table 185. +VNH Extended Syntax Commands

Command Function
+VNH=<hook> Enables or disables automatic DCE hang-ups.
+VNH? Displays the current parameter value.
+VNH=? Displays the range of supported parameter values.

Voice Commands: Speakerphone Operation

+VLS=<label> - Analog Source/Destination Selection

Use this general-purpose analog source/destination command to attach various analog devices to the system in voice mode.

Table 186. +VLS Commands

Command Function
+VLS=0 Speakerphone off.
+VLS=5 Disables/detaches microphone analog source (leaving speaker only) when speakerphone is in operation (phone mute feature).
+VLS=7 Speakerphone on. Attach internal speaker and internal microphone, DCE off-hook. Restores/attaches microphone along with speaker (normal speakerphone operation).

Table 187. +VLS Extended Syntax Commands

Command Function
+VLS=<value> Attaches or detaches an analog source or destination to the system in voice mode.
+VLS? Reports the current analog source/destination configuration, along with a listing of all event codes reported from the modem to the DTE under that configuration.
+VLS=? Queries the DCE for the range of supported configurations and the list of unsolicited event codes that the modem reports to the DTE under each configuration. For speakerphone, the configurations supported are 0, 5, and 7 (as explained above).

 

Voice Commands: Telephone Answering Device (TAD)

+VLS=? - Analog Source/Destination Selection and DTMF/Tone Reporting

Requests for the modem's DTMF/tone reporting capabilities are made using this command. For each system configuration in voice mode (i.e., speakerphone and answering machine), the modem reports the capabilities that are enabled for the configuration.

For each configuration, the modem indicates tone-reporting capabilities for each of the three different voice states: voice transmit data, voice receive data, and voice command state (voice idle).

TAD supports each of the following ITU-T Recommendation V.253 analog source/destination configurations.


Table 188. Analog Source/Destination Configurations

Label # Description
0 DCE on-hook, local phone connected to the telephone company.
1 DCE off-hook, DCE connected to telephone company.
2 DCE off-hook, local phone connected to DCE.
3 DCE off-hook, local phone connected to telephone company, DCE to local phone.
4 Speaker connected to DCE, DCE on-hook (playback messages).
5 Speaker connected to DCE, DCE off-hook (call screening).
6 Microphone connected to DCE, DCE on-hook (record greeting).
7 Microphone and speaker connected, DCE off-hook (speakerphone).

+VPR=<rate> - Select DTE/DCE Interface Rate

The +VPR command returns an OK result code for any rate but has no action.

Events Reported to the DTE

The modem returns OK when going off-hook in voice mode (+FCLASS=8). After answering in voice mode, the modem may send any of the following <DLE> shielded event codes to the DTE, as appropriate.

Table 189. <DLE> Shielded Codes Sent from DCE to DTE

Code Character Description
0 - 9, A - D, #, * DTMF tones.
a Answer tone.
b Busy tone.
c FAX calling tone.
d Dial tone.
e Data calling tone.
h Local phone on-hook.
H Local phone off-hook.
R Ring.
s Silence timer has expired.
<ETX> End of voice data transmission.
@ CAS tone detected.

<DLE> Codes Sent to DCE

For simple actions in voice mode, the modem may send any of the following <DLE> shielded event codes (in ASCII) to the DTE, as appropriate.

Table 190. <DLE> Shielded Codes Sent from DTE to DCE

Code Character Description
u Raise the volume by 1 dB.
d Lower the volume by 1 dB.
<ETX> End of voice data transmission.
! End of receive data state.

Note: The information supplied for this command does not affect host-based controller modems. The dialogue included with this command applies to controller-based modems only.

+VRA=<interval> - Ringing Tone Goes Away Timer

Use this command to set the ringing tone goes away timer before originating a call. The ringing tone goes away timer defines the amount of time the modem waits between ringing tones before assuming that the remote station has gone off-hook. The default is 50, and each value represents a 0.1 second increment.

Result codes:

Table 191. +VRA Extended Syntax Commands

Command Function
+VRA=<interval> Sets the ringing tone goes away timer.
+VRA? Displays the current value.
+VRA=? Displays the range of supported timer values.

+VRN=<interval> - Ringing Tone Never Appeared Timer

Use this command to set the ringing tone never appeared timer before originating a call. The ringing tone never appeared timer defines the amount of time that the modem waits for an initial ringing tone. If a ringing tone is not detected within this interval, the modem assumes that the remote station has gone off-hook. The default is 10, and each value represents a one-second increment.

Result codes:

Table 192. +VRN Extended Syntax Commands

Command Function
+VRN=<interval> Sets the ringing tone never appeared timer.
+VRN? Displays the current value.
+VRN=? Displays the range of supported timer values.

+VSD=<sds>,<sdi> - Silence Detection (QUIET and SILENCE)

Use this command to set the silence detection sensitivity (<sds>) and silence detection interval (<sdi>). The <sds> parameter defines the line noise sensitivity level in decibels.
The <sdi> parameter specifies the amount of time the modem waits before reporting silence to the DTE. It is used for determining the presumed hang-up (SILENCE), after which the modem sends <DLE>-s to the DTE. The default is 50 (5 seconds).

Result codes:

Larger values of <sds> indicate that the modem is to treat noisier line conditions as silence (see Table 193).

Table 193. <sds> Values

Value Function
<sds> = 128 Nominal level of sensitivity; - 40 dBm (default).
<sds> > 128 More aggressive; <sds> = 129 is - 39 dBm.
<sds> < 128 Less aggressive; <sds> = 127 is - 41 dBm.

Table 194. +VSD Extended Syntax Commands

Value Function
+VSD=<sds>,<sdi> Sets the silence sensitivity level and the silence detection interval.
+VSD? Displays the current silence detection sensitivity and silence detection interval.
+VSD=? Displays the range of supported values for the silence detection sensitivity and silence detection interval.

+VSM=<cml>,<vsr> - Compression Method and Sampling Rate Specifications

Use the +VSM* command to set the voice compression method and the sampling specification. The <cml> parameter identifies the compression method and the <vsr> parameter identifies the sampling rate.

Result codes:

Table 195. Compression Method

<cml> Compression Method Available Sampling Rates
128 8-bit linear. 7200, 8000, 11025
129 16 bit linear (default). 7200, 8000 (default), 11025
130 8-bit A-law. 8000
131 8-bit μ-law. 8000
132 IMA ADPCM. 8000
133 G.729. 8000

Table 196. +VSM Extended Syntax Commands

Command Function
+VSM=<cml>,<vsr> Sets the compression method and the sampling rate
+VSM? Returns the numeric and string labels of the compression method currently in use, and the sampling rate currently in use.
AT+VSM=? Reports the voice compression methods supported by the DCE and the voice sampling rates at which they are supported. The default is 129,800 (16-bit linear, 8.0 kHz).

* ITU-T Recommendation V.253 standardized this command. The standard version contains two additional parameters that are not supported by the USRobotics controller-based AT command set. For additional information on these parameters, see ITU-T Recommendation V.253.

+VSP=<value> - Speakerphone On/Off

Use this command to turn the speakerphone function on and off. Result codes:

Table 197. +VSP Commands

Command Function
+VSP=0 Speakerphone function off (default).
+VSP=1 Speakerphone function on.

Table 198. +VSP Extended Syntax Commands

Command Function
+VSP=<value> Turns the speakerphone on or off.
+VSP? Displays the current status of the speaker phone.
+VSP=? Displays the range of supported values.

+VTD=<dur> - Beep Tone Duration Timer

Use this command to set the default duration for DTMF/tone generation in 0.01 s increments. For DTMF digits, beep tone duration is the interdigit time. For tone generation, this number is the actual tone duration. The default tone duration is 100 or 1 s.

Result codes:

Table 199. +VTD Commands

Command Function
+VTD=<dur> Sets the duration for DTMF/tone generation.
+VTD? Displays the current beep tone duration timer.
+VTD=? Displays the range of supported values.

+VTR - Start Voice Transmission and Reception Process

Use this command to initiate full-duplex voice mode* in the DCE. In this mode, the DTE selects the analog source and sink through the +VLS command; the selections can be microphone and speaker or GSTN. The DCE is not required to perform any acoustic echo cancellation or line echo cancellation.

Result codes:

* See ITU-T Recommendation V.253 for further details on the voice states.

+VTS=<string> - DTMF and Tone Generation in Voice Mode

Use this command to produce a sequence of DTMF tones (or other tones, such as dial tone, busy, silence, etc.) as specified in the string parameter. String parameters are made up of a sequence of elements separated by commas. If the string does not supply a duration for a particular tone, then the DCE uses the duration designated by the +VTD command. The command can also generate a hook flash, +VTS=!.

Result codes:

Table 200. +VTS Extended Syntax Commands

Command Function
+VTS=<string> Generates DTMF tones according to the <string> parameter.
+VTD=? Displays the range of supported tones and duration.

Table 201. String Elements

String Elements* Description
A single character The valid single characters are 0 - 9, #, *, !, and A - D. This element always uses the default duration specified by the +VTD command.
A bracketed group [] A bracketed group has three components. It is used to generate a dual tone. The first component is the first tone^ in the dual tone. The second component is the second tone^ in the dual tone. The third component is the duration of the tones. The duration is specified in 0.01 s intervals. If one of the tone parameters is missing, its value is defaulted to 0 and that tone is not generated.
A curly bracketed group {} A curly bracketed group has two components. The first component is a DTMF tone or hookflash character (!). The second component is the tone duration. The duration of the tone is specified in 0.01 s intervals.

* The string definition provided in this text is a excerpt from the detailed definition provided in ITU-T Recommendation V.253 (02/98). Refer to Section 10.1.5.1.1 for a full description of the <string> parsing.
^ The tone specified in the bracketed group is a numerical value between 300 and 3300.

+VTX - Enter Voice Transmit Data State

Use this command to initiate the voice transmission process with the voice stream sent through the com port. Applications using the wave interface do not use the +VTX command.

There are two ways for the DCE to leave the voice transmit state:

Voice Modem Command Examples

The application issues AT commands to request actions by the modem, and the modem responds with standard TIA-602 result codes to tell the application that the requested action has been completed.

Notes for Speakerphone Examples

If the user decides to pick up his local (parallel) phone while in the middle of a speakerphone call, the DCE senses the transition and sends the application a <DLE>-H sequence. The application, which should always be screening for DLE-shielded codes in the background when the modem is in the voice mode, can then respond to the <DLE>-H (for example, by resetting speakerphone buttons or doing whatever else needs to be done with the speakerphone interface).

DLE-shielded codes that the modem sends to the application while in speakerphone mode are listed in Table 226.

Table 226. DLE-Shielded Codes

Command Description
DLE - c FAX calling tone detect.
DLE - e Data calling tone detect.
DLE - h Local phone went on-hook (hung up).
DLE - H Local phone went off-hook (picked up).

When the user is in the middle of a speakerphone call, call waiting (hold operation) can be initiated when the user hears the call waiting signal through the speaker. Call waiting entails the following communication between the application and the modem.

Command/Response Description Description
ATD! Put the current call on hold, and answer the new incoming call.
OK DCE responds. Original call is on hold, and the speakerphone user is connected to the second call.

To terminate the second call and return to the first, the application should again send the modem the ATD! command.

Command/Response Description
ATD! Terminate the second call and return to the original call.
OK DCE responds. Second call is terminated and the user is again connected to the original call.

Example #1: Initiating a Speakerphone Call (with Phone Muting During Conversation)

The speakerphone application is loaded. The modem is initially idle in data mode. The user then decides to pick up the phone to place a speakerphone call. Picking up the phone should initiate the following chain of events.

Command/Response Description
AT+FCLASS=8 The modem enters voice mode.
OK DCE responds. Now in voice mode.
AT+VGT=128 Set speaker volume to normal level.
OK DCE responds. Volume level is set.
AT+VLS=7 Attach internal speaker and microphone, DCE off-hook
OK DCE responds. Now in speakerphone mode. Phone off hook, dial tone audible, speaker and microphone ready to use.
ATD5551234 Provide dial string for DCE to place the call.
OK DCE responds. Number is dialed.

The call is placed through the phone network. The caller can hear ringback or busy signal from the phone being called. If the person at the other end picks up the phone, the caller and the person at the other end converse. If the speakerphone user decides to mute his speakerphone, the application sends the following to mute the speakerphone.

Command/Response Description
AT+VLS=5 Enters mute mode. Microphone is disconnected from the line, leaving the speaker only.
OK DCE responds. The microphone is no longer connected to the line, and the speakerphone is mute.

After a while, the speakerphone user decides to turn the microphone back on (mute off). This is done when the application issues the following command.

Command/Response Description
AT+VLS=7 No mute. Microphone is reattached to system along with speaker.
OK DCE responds. Speakerphone with both microphone and speaker is operational.

The conversation ends, and the user hangs up.

Command/Response Description
ATH Application tells the modem to terminate the call with standard AT command.
OK DCE responds.

The speakerphone is now on-hook. The speaker and microphone have been detached from the system, and the modem is now in data mode (+FCLASS=0).

Example #2: Initiating a Stored Number Speakerphone Call

The speakerphone application is loaded. The modem is initially idle in data mode. The user then decides to place a speakerphone call either by entering the number without first going off-hook or by selecting a number previously stored in the application. When the user tells the application to dial, the following events occur:

Command/Response Description
ATD5551234 Provide a dial string appended with a semicolon (;) for the DCE to place the call and go to command mode.
OK DCE responds, and the number is dialed.

The call is placed through the phone network in data mode. The modem stays in command mode, and the application should wait for the OK before sending next command.

Command/Response Description
AT+FCLASS=8 Put the modem into voice mode.
OK DCE responds: The modem is now in voice mode.
AT+VGT=128 Set the speaker volume to normal level.
OK DCE responds: The volume level is set.
AT+VLS=7 Start the speakerphone by attaching the internal speaker and microphone to the line; DCE off-hook.
OK DCE responds: Speakerphone mode is active. The phone is off-hook; dial tone is audible, and the speaker and microphone are ready to use.

The caller can hear ringback or busy signal from the phone being called. If the person at the other end picks up, the caller and the person on the other end converse. The conversation then ends, and the speakerphone user hangs up.

Command/Response Description
ATH The application tells the modem to terminate the call with a standard AT command.
OK DCE responds: The speakerphone is now on-hook. The speaker and microphone have been detached from the system, and the modem is now in data mode (+FCLASS = 0).

Example #3: Answering a Speakerphone Call

The speakerphone application is loaded. The modem is initially idle in data mode. In this mode, the modem is always screening for incoming calls.

Command/Response Description
RING DCE reports ringing from remote station. The user decides to pick up the phone, which should initiate the commands listed below in this table.
AT+FCLASS=8 Modem enters voice mode.
OK DCE responds. Now in voice mode.
AT+VGT=128 Speaker volume set to normal.
OK DCE responds. Volume level is set.
Command/Response Description
AT+VLS=7 Call is answered. Attach internal speaker and microphone to the line, DCE off-hook.
OK DCE responds. Now in speakerphone mode, connected to the line (call is answered).

The speakerphone user picks up the phone and hears the caller from the other end. Conversation continues for awhile. When it ends, the speakerphone user hangs up.

Command/Response Description
ATH DTE issues standard command to terminate call.
OK DCE responds. Speakerphone goes on-hook. Speaker and microphone are detached from system, and modem returns to data mode (+FCLASS = 0).

Note: When the local phone goes off-hook in the middle of a speakerphone call, the speakerphone disconnects, and the DCE returns <DLE>-H to the DTE.
When the speakerphone is on, call waiting (hold operation) is initiated by the following:

Command/Response Description
ATD! DTE sends hold command to DCE.
OK DCE responds.

Example #4: Receiving an Incoming FAX Call in Speakerphone or TAD Mode and Switching to FAX Mode

In this example, the sequence begins with the user or telephone answering device (TAD) taking the speakerphone off-hook and detecting a FAX calling tone from the other end.

Command/Response Description
<DLE>-c DCE detects FAX calling tone from the remote FAX and informs the application by sending DLE-c sequence.
AT+FCLASS=1 Application switches modem out of voice mode and into FAX mode.
OK DCE responds. Now in FAX mode, still off-hook and connected to incoming call.
ATA Application instructs modem to answer FAX call using standard AT commands.
OK DCE responds. The call is answered, and modem continues with procedures to establish connection and receive FAX transmission. The application software then disconnects the call when the FAX is done and returns to data mode (+FCLASS=0).

Example #5: Receiving an Incoming Data Call in Speakerphone or TAD Mode and Switching to Data Mode

In this example, the sequence begins at the point of the user or telephone answering device (TAD) taking the speakerphone off-hook and detecting a data calling tone from the other end.

Command/Response Description
DLE>-e DCE detects data calling tone from the remote modem and informs the application by sending DLE-e sequence.
AT+FCLASS=0 Application switches modem out of voice mode and into data mode.
OK DCE responds. Now in data mode, still off-hook and connected to incoming call.
ATA Application instructs modem to answer data call using standard AT commands.
CONNECT DCE responds. The call is answered, and modem continues with procedures to establish connection.

Example #6: Switching from Speakerphone Mode to TAD Mode

In this example, the sequence begins with the user in speakerphone mode and intending to put the other end on hold. The application may switch to TAD mode in hold state and play a music Wav file to the line.

Command/Response Description
AT+VLS=1 Applications switches modem out of speakerphone mode and into TAD mode by sending DLE-e sequence.
OK DCE responds. Now in TAD mode.
AT+VTX DTE selects voice transmit mode.
CONNECT DCE responds.
<Data> DTE plays music through modem to remote caller.
<DLE><ETX> DTE indicates end of voice transmit data.
OK DCE acknowledges switch back to voice command state.

The application may switch back to speakerphone mode by following the example to switch from TAD mode to speakerphone mode.

Example #7: Call Screening and Recording a Message Using TAD - IS101 <dle> Shielded Method

The TAD application is loaded. The modem is initially idle in data mode (+FCLASS = 0).

Command/Response Description
RING DCE reports ringing from remote station.
AT+FCLASS=8 The modem enters voice mode.
OK DCE responds.
AT+VGT=128 Sets speaker volume to normal.
OK DCE responds.
AT+VSM=132,8000 DTE selects IMA ADPCM with 8.0 kHz sampling rate.
OK DCE responds.
AT+VSD=128,0 DTE selects normal silence detection sensitivity, and a silence detection interval of 0 seconds. Disables silence detection.
OK DCE responds.
<DLE>-R DCE detects another ring and notifies DTE.
AT+VLS=1 The modem answers the call.
OK DCE is off-hook.

The TAD next plays its greeting message, issues a beep, and records the caller's message.

Command/Response Description
AT+VTX DTE selects voice transmit mode.
CONNECT DCE responds.
<Data> DTE plays greeting through modem to remote caller.
<DLE><ETX> DTE indicates end of voice transmit data.
OK DCE acknowledges switch back to voice command state.
AT+VTS=[933,0,120] DTE annotates greeting message with a 1.2 second beep.
OK DCE responds.
AT+VSD=128,50 DTE selects normal silence detection sensitivity and a silence detection interval of 5 s. Enables silence detection.
OK DCE responds.
AT+VLS=5 The speaker is attached to the system, and the modem is off-hook.
OK DCE is off-hook.
AT+VRX DTE selects voice receive mode.
CONNECT DCE agrees.
<Data> DCE delivers <DLE> shielded voice message to DTE.

The caller leaves a message and hangs up. The modem detects silence for a specified period of time, and then notifies the DTE that the message being recorded has ended.

Command/Response Description
<DLE>-s DCE issues presumed end of message after silence detection interval has elapsed.
<DLE>-! DTE signals end of voice receive state.
<DLE><ETX> DCE ends voice transmission to DTR, with this code, and returns back to voice command state.
ATH DTE issues standard command to terminate call. Speakerphone goes on-hook, speaker and microphone are detached from system, and modem returns to data mode (+FCLASS = 0).
OK DCE responds.

 

Example #8: Call Screening and Recording a Message with TAD Using the Wave Driver to Transmit and Receive Voice Samples

In this example, the TAD application is loaded. The modem is in data mode (+FCLASS=0), idle state.

Command/Response Description
RING DCE reports ringing from remote station.
AT+FCLASS=8 The modem enters voice mode.
OK DCE responds.
AT+VGT=128 Sets speaker volume to normal.
OK DCE responds.
AT+VSM=132,8000 DTE selects IMA ADPCM with 8.0 kHz sampling rate.
OK DCE responds.
AT+VSD=128,0 DTE selects normal silence detection sensitivity, and a silence detection interval of 0 seconds. Disables silence detection.
OK DCE responds.
<DLE>-R DCE detects another ring and notifies DTE.
AT+VLS=1 The modem answers the call.
OK DCE is off-hook.

The TAD next plays its greeting message, issues a beep, and records the caller's message. The application may transmit voice samples using the wave driver. The application may issue WAVE_OUT_OPEN and WAVE_OUT_WRITE messages to the wave driver. At the end of the greeting message, the application may issue the WAVE_OUT_STOP message to the wave driver.

Command/Response Description
AT+VTS=[933,0,120] DTE annotates greeting message with a 1.2 s beep.
OK DCE responds.

The application may receive voice samples using the wave driver. The application may issue WAVE_IN_OPEN and WAVE_IN_START messages to the wave driver.

Command/Response Description
AT+VSD=128,50 DTE selects normal silence detection sensitivity and a silence detection interval of 5 seconds. Enables silence detection.
OK DCE responds.
AT+VLS=5 Speaker is attached to system, and modem is off-hook.
OK DCE is off-hook.

The caller leaves a message and hangs up. The modem detects silence for a specified period of time, and then notifies the DTE.

Command/Response Description
<DLE>-s DCE issues presumed end of message after silence detection interval has elapsed.

At the end of the message, the application may issue the WAVE_IN_STOP message to the wave driver.

Command/Response Description
ATH DTE issues standard command to terminate call. DCE goes on-hook, speaker and microphone are detached from system, and modem returns to data mode (+FCLASS=0).
OK DCE responds.

Table 230. AT Voice Commands Summary

Command Description Reference*
+FCLASS=8 Enter voice mode. V.253 (02/98)
+VCID Caller-ID. V.253 (02/98)
+VDR Distinctive ring. V.253 (02/98)
+VEM Event reporting and masking. IS-101
+VGM Microphone gain.  
+VGR Receive gain selection. V.253 (02/98)
+VGS Speaker gain.  
+VGT Speaker volume control. V.253 (02/98)
+VIP Initialize voice parameters.  
+VIT DTE/DCE inactivity timer. V.253 (02/98)
+VNH Automatic hang-up control. V.253 (02/98)
+VLS Analog source/destination selection and DTMF/tone reporting. V.253 (02/98)
+VPR Select DTE/DCE interface rate.  
+VRA Set ringback goes away timer. V.253 (02/98)
+VRN Set ringback never came timer. V.253 (02/98)
+VRX Enter voice receive state. V.253 (02/98)
+VSD Set silence detection timer. V.253 (02/98)
+VSM Voice compression method. V.253 (02/98)
+VSP Speakerphone on/off.  
+VTD Set beep tone duration timer. V.253 (02/98)
+VTR Start full-duplex voice transmission and reception process.  
+VTS DTMF/tone generation. V.253 (02/98)
+VTX Enter voice transmit state. V.253 (02/98)

* All references are ITU-T recommendations unless otherwise noted.