ZyXEL Communications COMET 336, User Manual

Page: 61 / 70

54 Voice Operation
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 and processed.
The modem can discriminate between single and multiple DTMF tones received. If
calling tone, dial tone, busy tone, or answer tone is detected, this detection is reported
repeatedly (at reasonable intervals) if the DTE takes no action, and the tone continues to
be detected.
Table 7-2. Codes Sent to the DTE
Code Sent to DTE
Meaning
<DLE>0 Ð
<DLE>9, <DLE>*,
<DLE>#, <DLE>A
Ð<DLE>D
DTMF. Digits 0 through 9, *, #, or A through D detected by the modem, i.e., user has
pressed a key on a local or remote telephone. The modem sends only one <DLE> code
per DTMF button pushed.
<DLE>a
Answer Tone (CCITT). Send to the DTE when the V.25/T.30 2100 Hz Answer Tone
(Data or Fax) is detected. If the DTE fails to react to the code, and the modem continues
to detect Answer tone, the code is repeated as often as once every half second.
<DLE>b
Busy. Sent in Voice Receive Mode when the busy cadence is detected, after any
remaining data in the voice receive buffer. The modem sends the busy <DLE>b code
every 4 seconds if busy continues to be detected and the DTE does not react. This
allows the DTE the flexibility of ignoring what could be a false busy detection.
<DLE>c
Calling Tone. Sent when the T.30 1100 Hz Calling Tone (Fax Modem) is detected in
any of the voice operating modes. The modem assumes that the calling tone is valid and
sends this code only after 4 seconds of proper cadence has been detected. If the DTE
does not react to the <DLE>c, and calling tone continues, the code is sent again as often
as once every 4 seconds.
<DLE>d
Dialtone. Sent in Voice Receive Mode when dial tone is detected after any remaining
data in the voice receive buffer. The modem sends the <DLE>d code every 3 seconds if