56K V.92 Data, Fax, and Voice Chipset
80 Intel Confidential Programmer’s Guide
6. IS-101 VOICE MODE AT COMMANDS
The 56K FastPath chipsets implement a voice mode AT command set that allows a DTE to record
and play back voice messages. In addition to this programmer’s guide, the Intel IS-101 Voic e
Application Note, shows a number of ways to use these AT commands. This product is compatible
with the EIA/TIA IS-101 voice command set. This section lists supported commands and a detailed
description of each command (see Table6-1 on page 82). When multiple commands are placed on
a line, a semicolon (;) must be placed after each voice (and fax) command.
See Table 2 -6 and Table 2-7 on page 19 for voice character pairs (DTE-to-DCE and DCE-to-DTE).
Note: To originate a call, to answer, and to hang up, use the ATD, AT+VL S≠0, and AT+VL S=0
commands, respectively.
Each command may be used as follows:
+V<command>? Read current setting
+V<command> = ? Read permissible settings
+V<command> = <parameter> Set parameter
For example, AT+FCLASS? determines whether the modem is configured for data (or fax) mode
or voice mode. AT+FCLASS=? determines which data/fax/voice modes are supported by the
modem. AT+FCLASS=n switches between voice mode and data mode.
The modem exchanges streams of data with the DTE while executing the commands for voice
playback (AT+VT X) and record (AT+VR X) and while in voice command mode (with either the
modem being off-hook or using the local phone — AT+VLS =n). In these modes, the DCE
searches for DTMF, calling tone, and dial tones and reports them to the DTE whenever they are
detected. Detection information and data stream terminators are passed between the DTE and DCE
by first sending an ASCII <DLE> character ($10h) followed by a special character. Special
characters in the data stream are used as follows:
any data ... <DLE><ETX> end of data stream ($10 $03)
any data ... <DLE><DLE> single $10 in data stream
any data ... <DLE><X> X is a special character,
delete both <DLE> and X from
the data stream
When the DTE transfers data to the modem during playback mode (AT+VTX command), the DTE
must insert a <DLE> for each <DLE> in the original data stream. When data is no longer available,
the DTE must add the stream terminator <DLE><ETX> to the end of the data stream. If the modem
detects the two terminating characters <DLE><ETX> within the data stream, it transmits the data
immediately to the remote modem without waiting for the buffer to fill up. To abort playback mode
without waiting for the modem to empty the internal modem buffer, send
<DLE><CAN><DLE><ETX>. Immediately aborting the playback mode eliminates long delays
between receiving a DTMF tone or keyboard abort and starting a new function such as playing
back or recording a new message.
When the modem transfers data to the DTE during record mode (AT+VRX command), the DTE
must filter the data stream by removing all character pairs beginning with <DLE>. The DTE also
must recognize <DLE><ETX> as the stream terminator. Upon detecting <DLE><DLE>, the DTE
must reinsert a single <DLE> in its place. The modem buffers up to 512 bytes of voice data
received from the SAFE analog-to-digital converters if the DTE cannot read the data immediately.