DTE to Modem
Modem to DTE Description and Interpretation
RING Sometime later, a call is received.
#CLS=8 Configure the modem for Voice Mode.
OK The modem agrees, and is now set up for voice, but
the DTE can change things during the discrimination
phase.
#BDR=16 The DTE knows that the compression requires a 38,400
bits/s speed, so it forces this as the new speed.
OK This OK message is sent at 9600 bits/s, but the modem
then switches to 38,400 bits/s. The S30 timer is now
active.
#VSS=2 This enables default silence deletion.
OK The modem confirms command reception.
A The DTE answers. (This is where the DTE can let
another RING go by to process Caller ID.)
VCON The modem is now in Online Voice Command Mode. DTMF
and calling tone detection is enabled. If FAX or data
calling tones are detected, the DTE can change to Fax
or Data Mode.
#VTX The DTE immediately switches to Voice Transmit Mode
to send out a short greeting.
CONNECT The modem says: Send me the ADPCM data.
<Data> The DTE sends a previously recorded message from a
very fast talking person: Hello, this is Dave. Press *
to send a FAX, # for help, or leave your message at
the beep. (The caller can enter DTMF tones at any
time, which the DTE can take into account, or calling
tone can still be detected.)
<DLE> This ends the greeting message.
<ETX>
VCON The modem switches back to Online Voice Command Mode.
#VTS=# The DTE sends # as the beep.
VCON The modem is still able to receive DTMF or Calling
tone here.
#VRX Enter Receive Mode. Now the modem is clocking
silence, as well as DTMF, and recording whatever the
caller says.
<DLE>5 #VSP must have been set to 35, since 3.5 seconds
later the modem sends this indication of silence
period expiration. No ADPCM data was sent to the DTE,
because the data pump deleted all 3.5 seconds of
silence. This tells the DTE that nobody is talking.
! The DTE issues a key abort to switch to Online Voice
Command Mode.
<DLE> The modem exits Voice Receive Mode and switches to
<ETX> Online Voice Command Mode.
VCON
#CLS=0 The DTE received no voice data, just the silence
indicator after a 3.5 second wait. Since there was no
calling tone and the user never entered any DTMF
tones, the DTE assumes it must be a calling data mode.
If the data handshake fails, the modem does not hang
up the line thus giving the DTE another chance to try
the FAX again.
OK The modem is now a data modem.
A The modem pretends that it just got RING, try V.22
bis/V.42, etc.
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