Going to exhibit at VCF East -- need help

[Synoptic]

Hi !
I'm going to exhibit at VCF East in April.

I'm currently working on featuring the Clone with other computers. I would like to use a modem to dial into the clone.
I currently have setup an external USRobotics modem using a null-modem cable (the one with some of the lines crossed) between the USRobotics and the Clone since the two devices are considered "slave devices". The modem answers, but I cannot get anything to display into the terminal.

If I use a regular serial cable between the PC and the clone, then it works.
Why is that ? What do I need to fix ?

[AltairClone]

The Altair and the modem are both wired as DCE, so yes, you will need a null modem cable, however, you need to know the details of how the null modem is wired to know for sure why it’s not working. Since the Altair Clone does not have all modem control signals on its DB25, jumpering pins 6, 8, and 20 on the MODEM side of the null modem cable will probably work.

Mike

[Synoptic]

The Altair and the modem are both wired as DCE, so yes, you will need a null modem cable, however, you need to know the details of how the null modem is wired to know for sure why it’s not working. Since the Altair Clone does not have all modem control signals on its DB25, jumpering pins 6, 8, and 20 on the MODEM side of the null modem cable will probably work.

Mike

Thanks. Not sure what you mean by "jumping".
I have the necessary parts to build a custom cable. Would you mind giving me a pinout?

[Synoptic]

Ok, for some reason, it now works !

It's was a matter of setting the right jumper switches correctly on the modem.

Now, it works using my Compaq Portable, but it does not using the Osborne Executive internal modem. I'll have to dig into this.