Status register 4, Flash (!) / on time, Flash (!) / off time – Maxim Integrated Teridian V.22 bis Linux Softmodem for 73M1822/73M1922 MicroDAA User Manual
Page 28: S120, Accepted answer tone frequencies

V.22 bis Linux Softmodem for 73M1x22 MicroDAA User Guide
UG_1x22_043
28
Rev. 1.5
S92
Status Register 4
4
pulse dialing allowed.
Bit
Value
Bit 0
Reserved
Bit 1
Reserved
Bit 2
0
Pulse dialing disabled
1
Pulse dialing enabled
All others bits are reserved.
S86
Flash (!) / On Time
n
1 – 211 in 10 ms unit
50
500 ms
S87
Flash (!) / Off Time
n
1 – 211 in 10 ms unit
50
500 ms
Note:
See also S14 and S22
S120
Accepted Answer Tone Frequencies
Enables control over what the modem will qualify as answer tone. By default, the modem
functions as it has in the past. (Default = $35)
Bit 0
1650Hz – V21 Marks (default)
Bit 1
1300Hz – V23 Marks
Bit 2
2100Hz – ITU Answer Tone (default)
Bit 3
Reserved
Bit 4
2225Hz – Bell Answer Tone (default)