It's a Windows problem. I had the same problem with a Compaq laptop I was fixing for a friend. I have actually found that, if the Windows installation process has a problem, it's actually a quite common problem. Reinstall Windows using whatever came with the machine. Most likely, when NEC did the install, something didn't complete properly and when they completed the installation, it disabled the ability to dial-up. I've found that reinstalling Windows again resolves the problem. Good luck.

AJ