RAS through serial connection

I am trying to set up two NT4.0 WorkStations using only a serial connection using RAS. It appears as though it is working about half. I can dial-in and Map a Drive. But my boss believes we should have two way comms and currently it is only one way. Currently there is no modem in place just a serial cable. We have checked the PIN outs and gone through the RAS setup 100 times. Still I can not ping either way nor see the other machine in Network Neighborhood. I can only map a drive. Is this correct or is there something we are missing? Please ANY help is appreciated.

Thank you
Bluhippo@earthlink.net