HP 24SII - Manual (Page 68)

NOTE: Using RAMEXEC to select another computer port is not
suggested. This is because RAMEXEC does not provide full duplex
communication so you cannot see the
On Line or Busy message if
you attempt to use RAMEXEC to determine whether or not you got
connection to the other computer port.
Modem sharing can be achieved with a computer-to-computer
connection through the Model 24SII DES.
Make the connection to the modem port by sending the Port Select
Code, the module number (1 to 6) and port number (1 to 4) the
modem is connected to followed by a Enter/Return or line feed
character. The model 24 will respond with an
On Line message if the
modem is available or a Busy message if the modem is currently
connected to another computer port. Proceed with your normal
modem communications once you receive the
On Line message from
the Model 24SII DES.
It is suggested that the computer make the connection to the modem
port on the Model 24SII DES from within your desired modem
package. You must be in a full duplex mode within your modem
package. You must also configure your modem package to
communicate with the same serial port parameters that your computer
normally uses to print with (i.e., baud rate, etc.).
A common mistake is to configure your communications package to
match your modem's serial parameters (baud rate, word size, etc.)
and not the Model 24SII's serial parameters. Keep in mind that you
are physically connected to the Model 24SII DES, not the modem.
The Model 24SII DES will do any necessary serial parameter
conversions between the computer and the modem.