foolproof serial ports?

[q-funk@megacom.net (Martin-Eric Racine)]

Since tonight, my modem doesn't correctly receive its init string,
which seems to be caused by improper communication between modem
and PPPD/CHAT. Result is a connection at a slow 19200 baud.

Since pretty much all comm packages (ConNect, PPPD/CHAT) are supposed
to be able to config the ports themselves, why does disabling the CPX
(serial.cpx) result in the modem running at only 19200 bauds?

Shouldn't PPPD be able to access the ports based on .ppprc settings?
Why would anyone need any CPX if this is the case?