PPP and seriel connection

<Now it is possible that the modems I had available then were different <from current ones, this was in 1993 and I was working with 1200 or 2400 <baud modems. No difference. DC on the line was used to sense off hook. It's possible to ignore the associated line status bit, standard software(dialers, terminal emulators" would likely look at it and indicate an error. Most modems use this to indicate a live line and not already in use. Carrier tone (dial tone) is the next level up to indicating a live line and dialing is possible. In any case if these are worked around one modem must be originate and the other answer so the signal sense is correct. While it could be handy and made for a real simple two wire interconnect it's slower than serial direct. <If you can give me references to documents describing modem and phone lin <electrical standards I would appreciate it. Not handy, I'm sure it's on the net. Allison