ZyXEL Communications COMET 336 User Manual page 66

Recording can be canceled only via two events:
1. The DTE sends any character to the modem. This is the key abort, and is the normal
method of terminating the receive mode.
2. The S30 Disconnect Inactivity timer expires, which is generally an undesired event.
7.2.7 Voice Playback
To effect playback of a message recorded via a handset or microphone, or of a message
recorded during a voice call, the DTE must configure the modem for Voice Mode
(#CLS=8) and select the proper relay setup (#VLS) to instruct the modem whether to
use the handset or speaker. The modem responds to the #VLS command by issuing a
relay activate command to select the input device. The hardware must provide a means
of selecting a handset and/or microphone instead of the telephone line, as this input
device. When a device other that the telephone line is selected, the modem immediately
enters Online Voice Command Mode (indicated by VCON). DTMF detection is thus
enabled as soon as the DTE selects the device, such as a handset, although the user still
needs to physically pick up the telephone before he can issue DTMF tones. Once
selected, however, the user can indeed pick up the telephone and press buttons. Even if
the DTE has not entered Voice Receive or Transmit Modes (#VTX or #VRX), these
DTMF tones are delivered via shielded codes, identically to when a physical telephone
connection exists but the DTE has not yet commanded receive nor transmit.
When the DTE decides to play the message, it issues the #VTX command, and the
modem immediately switches to Voice Transmit Mode. Since the speaker or handset is
already switched in, the modem immediately issues the CONNECT message indicating
that the modem is in Voice Transmit Mode and is expecting voice data from the DTE.
A subsequent <DLE><ETX> has to be issued to switch back to Online Voice Command
Mode.
Volume Adjustment During Record
The record volume is adjusted automatically by an automatic gain control (AGC)
circuit.
Volume Adjustment During Playback
The playback volume of the headphone and speaker outputs and handset can be adjusted
by the #TL command (Section 7.3.2).
7.2.8 Voice Call Termination
Local Disconnect
The DTE can disconnect from a telephone call by commanding a mode change to Online
Voice Command Mode (if not already in it), and by issuing the H command.
Remote Disconnect Detection
Voice Operation 59