Since RH5.9/RH6.0 are kernel2.2 based, pppd should be using
(e.g.) /dev/ttyS0 instead of (e.g) /dev/cua0 for dialing
out. It doesn't, which means annoying messages get spewed to
console and logs about deprecated use of /dev/cua0
AFAIK, it's just using the /dev/modem symlink, which
may be pointing to cua0 from an earlier install.
I have verified that ppp doesn't use /dev/cua0 unless /dev/modem is
symlinked to it. Please rerun modemtool where modemtool's release is
>= 1.21-6 (which creates properly named devices).