US Robotics 56K USB Modem User Manual page 89

Events Reported to the DTE
The modem returns OK when going off-hook in voice mode (+FCLASS=8). After answering in voice mode,
the modem may send any of the following <DLE> shielded event codes to the DTE, as appropriate.
Table 189. <DLE> Shielded Codes Sent from DCE to DTE
Code Character
0—9, A—D, #, * DTMF tones.
a Answer tone.
b Busy tone.
c FAX calling tone.
d Dial tone.
e Data calling tone.
h Local phone on-hook.
H Local phone off-hook.
R Ring.
s Silence timer has expired.
<ETX> End of voice data transmission.
@ CAS tone detected.
<DLE> Codes Sent to DCE
For simple actions in voice mode, the modem may send any of the following <DLE> shielded event codes
(in ASCII) to the DTE, as appropriate.
Table 190. <DLE> Shielded Codes Sent from DTE to DCE
Code Character
u Raise the volume by 1 dB.
d Lower the volume by 1 dB.
<ETX> End of voice data transmission.
! End receive data state.
Note:The information supplied for this command does not affect
host-based controller modems. The dialogue included with
this command applies to controller-based modems only.
Description
Description
56K USB Modem
User Guide
Command Reference - 83