I had to remote access the server meaning through modem and assign the IP to the acceessed client. I did:
1) the modem (connected to com1) was setup at answering mode.
2)issued cmd: "pppd /dev/ttyS0"
3) wrote to: "/etc/ppp/options.ttyS0" --> 192.168.0.200:192.168.0.201
4) the remote client was successfully accepted by the server. and ppp connection established without asking for password.
5)but when the server was rebooted, the modem was not answered by the server.

so my problems are:
a) how to permanently create pppd server?
b)how to assign password during pppd connection. I want to use local user-password. for example, I have a user /home/jam and I want to give pppd authentication to jam only. ie I want to ask password before allowing remote log in.