Lucent Technologies Inc.
67
Manual
August 2000
Venus AT Command Reference Manual
AT Voice Commands
(continued)
AT+VSD=<sds, sdi>—Silence Detection (QUIET and SILENCE)
This command sets both the silence detection sensitivity (<sds>) and silence detection interval (<sdi>). Larger val-
ues of <sds> indicate that the modem is to treat noisier line conditions as silence (see Table 124). The valid range
for each field is 0—255.
Table 124. <sds> Values
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 DTE. The default is
50 (5 seconds).
AT+VTX—Enter Voice Transmit Data State
This command causes the modem to begin the voice transmission process with the voice stream sent 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 the voice transmit state:
1. Modem receives <DLE>-<EXT>in voice stream.
2. DTE/DCE inactivity timer expires.
AT+VRX—Enter Voice Receive Data State
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.
There are two ways for the DCE to leave the voice receive state:
1. Modem receives <DLE>-! from the DTE.
2. Upon expiration of the silence detection timer, the modem passes <DLE> shielded event codes indicating a pre-
sumed hang-up (<DLE>-s) or presumed end-of-message (<DLE-q>).
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.
AT+VSD?
Returns the current silence detection sensitivity and silence detection interval.
AT+VSD=?
Returns the range of supported values for the silence detection sensitivity (0—255) and silence
detection interval (0—255).
