Rockwell RCV144ACx, Command Reference Manual

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AT Command Reference Manual
1048 7-5
Table 7-2. Codes Sent to the DTE
Code Sent to DTE Meaning
<DLE>0 –
<DLE>9, <DLE>*,
<DLE>#, <DLE>A
–<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 dial tone continues to
be detected and the DTE does not react. This allows the DTE the flexibility of ignoring what could be
a false dial tone detection.
<DLE>e European Data Modem Calling Tone. Sent when the V.25 1300 Hz Calling Tone (Data Modem) is
detected in a voice submode. 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>e
and calling tone continues, the code is sent again as often as once every 4 seconds.
<DLE>f Bell Answer Tone. Sent when Bell 2225 Hz Answer Tone (Data) 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 every
1/2 second.
<DLE>h Hung Up Handset. Sent immediately when the modem detects that the local handset has hung-up
(i.e., has transitioned from off-hook to on-hook) while in any of the three voice submodes.
<DLE>o Overrun. Sent in Voice Receive Mode if the voice receive data buffer overflows, in which case, the
latest data is lost in favor of retaining the oldest data in the buffer. (The DTE may not have been
reading data from the modem lately.) The modem inserts the <DLE>o at the end of the buffer, thus
marking the location where data was lost by the DTE. The modem does not append <DLE>o codes
to the buffer contiguously. If more than one data byte is lost before the DTE begins reading again,
there is only on <DLE>o code in the data stream. However, if the DTE resumes reading, and then
once again allows the buffer to overflow, a new <DLE>o is appended to the data by the modem.
Thus, the <DLE>o does not indicate how many bytes of contiguous data has been lost, but may
report multiple gaps of lost data in the data stream.
<DLE>q Quiet. Sent in Voice Receive Mode following any remaining data in the receive voice buffer when the
silence detection timer (#VSP) expires and there has been voice data passed to the DTE. Note that
with #VSS=0, the Quiet message never occurs. In general, <DLE>q is sent if first there was sound,
and now there is no sound, and means that somebody has stopped talking, and according to the
criteria selected in the #VSP and #VSS settings, is probably not going to start again. If the DTE
ignores the <DLE>q code, the modem automatically resets its timer and sends the code again if the
#VSP time period again expires. This allows the DTE time to react to what may be a false silence
detection.