Call-in & call-out on the same line

[Guy Harris]

>Actually, it's pretty easy on a Sun.  You have to build some cu devices.

*And* you might have to reconfigure your kernel to turn "soft carrier"
off for the port(s) in question; that's a common cause of failure when
people try to use the dial-in/dial-out device.  (In a future release, I
expect this to be done by a flag in "/etc/ttytab", so you don't have to
reconfigure your kernel.  Of course, you don't want to run a generic
kernel any longer than you have to, anyway....)