Apple Express Fax/Modem - Manual (Page 117)

Call management
Your modem is designed to manage communications with Express Fax,
AppleTalk Remote Access, and your communications program. This function
is known as call management.
Your computer has just one physical modem port, which appears on the back
panel where your modem is connected to the main logic board. To manage
calls, the Express Modem software creates three “logical” ports—that is, non-
physical ports. The Express Modem software generally sends incoming data
to the logical port associated with the program. In other words, the modem
sends fax data to the fax logical port, and so on. (For an exception to this rule,
read “Setting auto-answer at the application level” in this chapter.)
Even with call management, your modem can still only connect to one
telephone line at a time. If your modem is in use, and one of your
communications programs tries to dial out to a different number, a Modem in
use message is displayed in that program.
The modem serves your programs according to the following set of priorities:
Type of program Priority
Data User programs
MacTerminal and other CTB Highest priority over other program types to allow
terminal emulator programs user control of modem at all times for both sending
or front-end programs, such and receiving data.
as AppleLink
Data Server programs
AppleTalk Remote Access Lower priority than Data User. Allows Data Server
and other servers to run in background while user
program controls modem. When Data User program
releases modem, Data Server is ready for incoming calls.
Fax Server programs
The Express Fax software Same priority as Data Server. Runs in background
while user program controls modem. When Data User
program releases modem, Fax Server is ready for
incoming calls.
105 T E C H N I C A L I N F O R M A T I O N