3Com 56k User's Manual And Reference page 69

Register Default
S15 (Continued)
S16 0
S17 0
S18 0
S19 0
S20 0
S21 10
Technical Reference
Function
Bit Value Result
3 8 Disable MNP handshake
4 16 Disable MNP level 4
5 32 Disable MNP level 3
6 64 MNP incompatibility
7 128 Disable V.42 operation
To disable V.42 detect phase, select the total of the values for bits 3 and 7. (S15=136{the sum
of values 8 and 128})
Reserved
Reserved
Test timer for &T loopback testing
Sets the time in seconds of testing before the modem automatically times out and terminates
the test
When set to 0, the timer is disabled
Valid range is 1-255
Sets the duration, in minutes, for the inactivity timer
The timer activates when there is no data activity on the phone line; at time-out the modem
hangs up
S19 = 0 disables the timer
Reserved
Sets the length, in 10-millisecond units, of breaks sent from the modem to the computer;
applies to MNP or V.42 mode only
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