Voice Operation

		Voice Operation

You should use the voice software supplied with your modem to send and receive verbal messages or record telephone conversations. Consult the documentation associated with that software for more information.

Summary of the AT Voice Command Set :

The AT Voice Command set follows a modified IS-101 architecture. The commands are sent through the comm port, but the data path is sent either through the comm port or through a DMA channel using the wave driver. The following tables show a summary of the AT Voice Command Set.

**The AT Voice Command Set**
AT+FCLASS=8	Enter voice mode
AT+VIP	Initialise voice parameters
AT+VCID	Caller ID
AT+VDR	Distinctive ring
AT+VGT	Speaker volume control
AT+FMI?	Report manufacturer ID
AT+FMM?	Report product model information
AT+FMR?	Report product revision level
AT+VIT	DTE/DCE inactivity timer
AT+VNH	Automatic hang-up control
AT+VTD	Set beep tone duration timer
AT+VLS	Analog source/destination selection and DTMF/tone reporting
AT+VSD	Set silence detection timer
AT+VRA	Set ringback goes away timer
AT+VRN	Set ringback never came timer
AT+VTS	DTMF/tone generation
AT+VTX	Enter voice transmit state
AT+VRX	Enter voice receive state
AT+VSM	Voice compression method
AT+VEM	Event reporting and masking
AT+VGR	Receive gain selection

**The AT Voice Command Set Not Defined In IS-101 Specification**
ATS32	Synthetic ring volume
ATS33	Synthesised ring frequency

+FCLASS=8 Enter Voice Mode

The command AT+FCLASS=8 puts the modem in voice mode.

AT+FCLASS? Returns the current DCE mode

AT+FCLASS=? Queries the DCE for the range of modes supported.

+VIP Initialise Voice Parameters

The command AT+VIP causes the modem to initialise all the voice parameters to their default values. The command has no effect on the +FCLASS setting.

+VCID Caller ID

With this command caller identification is enabled/disabled.

AT+VCID=0 Disable caller ID.

AT+VCID=1 Enable, formatted caller report.

AT+VCID=2 Enable, unformatted caller report.

AT+VCID? Returns the current caller ID mode.

AT+VCID=? Queries the DCE for the range of supported caller ID report formats.

+VDR=(enable,report) Distinctive Ringing & Cadence Report

This command will enable the distinctive ringing feature. This will allow a report of DROF/DRON to follow an exact ring cadence coming over the phone line.

AT+VDR? Returns the current values of (enable,report).

AT+VDR=? Queries the DCE for the range of supported distinctive ring configurations. DCE returns: (0,1),(0-255).

+VGT=level - Speaker Volume Control

This command will enable the speaker volume control.

level range is 0-255.

level = 128: Nominal volume level for sending to speaker.

level = value greater than 128: Increase volume above nominal level.

level = value less than 128: Decrease volume below nominal level.

+VGR=gain - Receive Gain Selection

This command will enable the receive microphone gain control.

gain range is 0-255; the only useful range is 121-134.

gain = 128: Nominal volume level for receive gain from microphone.

gain = value greater than 128: Increase gain above nominal level.

gain = value less than 128: Decrease gain below nominal level.

+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).

AT+VEM? Returns the current values of the mask.

AT+VEM=? Queries the DCE for the range of supported service level events.

DCE Identification Commands

This command will enable DCE identification.

AT+FMI? Report manufacturer ID.

AT+FMM? Report product identification (model).

AT+FMR? Report version or revision level.

+VIT=timer - DTE/DCE Inactivity Timer

This command sets the DCE's value for the DTE/DCE inactivity timer. The units are in seconds.

AT+VIT? Returns the current value of the timer.

AT+VIT=? Queries the DCE for the range of supported values.

+VNH=hook - Automatic Hang-up Control

This command causes the DCE to enable or disable automatic hang-ups in the data and facsimile modes.

hook=0 The DCE retains automatic hang-ups (which is the way in the other non-voice modes).

hook=2 The DCE disables automatic hang-ups in the other non-voice modes. The DTE only performs logical hang-ups (returns the "OK" result code).

+VTD=dur - Beep Tone Duration Timer

This command sets the default duration for DTMF/tone generation in 0.01 second increments. The range of dur is 0 to 400.

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

This command will cause the modem to produce a sequence of DTMF tones (or other tones, such as dial tone, busy, silence, etc.) as specified in the string parameter.

AT+VTS? reports the current string parameter

AT+VTS=? reports the range of frequencies supported for tone generation, as well as tone duration. e.g. (300-3000),(300-3000),(0-400).

+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, the modem reports the capabilities which are enabled for the configuration. Also, 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 (Telephone Answering Device) supports each of the following IS-101 analog source/destination configurations:

AT+VLS=0 DCE on-hook, local phone connected to Telco.

AT+VLS=1 DCE off-hook, DCE connected to Telco.

AT+VLS=4 Speaker connected to DCE, DCE on-hook (playback messages).

AT+VLS=5 Speaker connected to DCE, DCE off-hook (call screening).

AT+VLS=6 Microphone connected to DCE, DCE on-hook (record greeting).

+VSD=sds,sdi - Silence Detection (Quiet and Silence)

This command sets both the silence detection sensitivity (sds), and silence detection interval (sdi).

Larger values of sds indicate that the modem is to treat noisier line conditions as silence.

sds = 128; Nominal level of sensitivity; -40 dBm (default).

sds = value greater than 128; More aggressive; sds = 129 is -39 dBm.

sds = value less than 128; Less aggressive; sds = 127 is -41 dBm.

The sdi specifies the amount of time the modem shall wait before reporting silence to the DTE. It is used when determining:

Presumed hang-up (SILENCE), after which the modem sends DLE-s to the DTE.

Default is 5 seconds.

+VTX Enter Voice Transmit Data State

Using this command will cause the modem to begin the voice transmission process with the voice stream sending through the comm port. Applications using the wave interface do not use the AT+VTX command.

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

1. Modem receives <DLE>ETX in voice stream.

2. DTE/DCE inactivity timer expires.

+VRX Enter Voice Receive Data State

Using this command enables the modem to begin voice receive state with the voice stream received through the comm port. Applications using the wave interface do not use the AT+VRX command. The modem returns the CONNECT result code to the DTE.

The DCE leaves voice receive state when:

1. Modem receives <DLE>! from the DTE.

2. Upon expiration of the silence detection timer, the modem passes <DLE> shielded event codes indicating presumed hang-up (<DLE>s), or presumed end-of-message (<DLE>q).

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

This command enables the compression method and sampling specifications where cml=compression method label, and vsr=voice sampling rate.

AT+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 128, 8000 (8-bit linear, 8.0 kHz).

128, 8-bit LINEAR, (7200, 8000, 11025).

130, 8-bit ALAW, (8000).

131, 8-bit ULAW, (8000).

132, IMA-ADPCM, (8000).

+VRA=interval - Ringback Goes Away Timer

The modem uses the ringback goes away timer when originating a call. The interval range is 0-255, and the default value is 50.

This command sets this timer to the amount of time the modem shall wait between ringbacks before assuming that the remote station has gone off-hook.

+VRN=interval - Ringback Never Appeared Timer

The modem uses the ringback never appeared timer when originating a call. The interval range is 0-255, and the default value is 10.

The AT+VRN command sets this timer to the amount of time that the modem shall spend looking for an initial ringback. If ringback is not detected within this interval, the modem shall assume that the remote station has gone off-hook.

Tone and status monitoring

The modem can detect specific tones and other status information, and report these to the DTE while in any of the three voice sub-modes. The modem simultaneously looks for 1300 and 1100 Hz calling tones when answering, and for CCITT (ITU-T) and Bell answer tones when originating. The modem can also detect dial or busy tones in any of the three voice sub-modes. All detected tones, as well as certain other status's addressed in the following table such as "silence" and "teleset-off-hook" (i.e. handset off hook) are reported as shielded codes. When in on-line voice command mode or voice transmit mode, the codes in the following table are sent to the DTE immediately on verification by the modem of the associated tone, status or cadence.

**Shielded codes sent to the DTE**
<DLE>0 - <DLE>9 <DLE>* - <DLE># <DLE>A - <DLE>D	DTMF digits 0 to 9, *, # and A to D detected by the modem.
<DLE>a	Answer tone detected.
<DLE>b	The BUSY signal is detected.
<DLE>c	The fax calling tone is detected.
<DLE>d	Dial tone is detected.
<DLE>e	The data calling tone is detected.
<DLE>h	Local phone on-hook.
<DLE>H	Local phone off-hook.
<DLE>R	Ring tone detected.
<DLE>s	The silence timer has expired.
<DLE>@	CAS tone detected.
<DLE><ETX>	End of voice data transmission.

Shielded codes sent from the DTE
<DLE><ETX> End of voice data transmission.
<DLE>u Bump up the volume by 1 dB.
<DLE>d Bump down the volume by 1 dB.
<DLE>! End receive data state.

**Shielded codes sent from the DTE**
<DLE><ETX>	End of voice data transmission.
<DLE>u	Bump up the volume by 1 dB.
<DLE>d	Bump down the volume by 1 dB.
<DLE>!	End receive data state.

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 or processed.

AT Voice Command Set Not Defined In IS-101 Specifications

S32 Synthetic Ring Volume - This command will provide a synthetic ring volume in dB with an implied minus sign. The default = 10.

S33 Synthetic Ring Frequency - This command will provide a synthetic ring frequency. The valid values are 0-5, with 0 = disabled, and 1-5 enabling varying ring frequencies. The default = 0.