Apple Express Fax/Modem - Manual (Page 118)

Setting auto-answer at the application level
Express Fax, AppleTalk Remote Access, and your communications program
all contain an auto-answer command that sets your modem to answer calls
automatically. Each program’s auto-answer setting—the S0 register—affects
call management in the following ways:
m Only a Data User or a Server program (Fax or Data) is open.
M If the program is set to auto-answer, the modem answers after the
number of rings designated in the S0 register of the open program.
M If S0=0, the modem answers only when the manual answer command is
given.
m Both a Data User and a Server program (Fax or Data) are open.
M If both programs are set to auto-answer, the modem answers after the
number of rings designated in the Data User program.
If the call is a fax call, it is passed to the fax server.
If the call is intended for the data server, it is not passed to the data server
(data user programs take precedence over data server programs) because
the data port cannot distinguish between the two data programs.
M If the Data User program has set S0=0, the modem will not answer.
m Both Fax and Data Server programs are open.
M If both programs are set to auto-answer, the modem answers after the
number of rings equal to the minimum of the two S0 values. The call is
passed to the correct logical port.
M If one program has S0=0, the call is passed to the program whose S0>0,
if appropriate. If both server programs have their respective S0=0, the
modem does not answer, but calls may still be placed.
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