Win95 RAS Error??

I have an attorney’s home pc that has connectivity issues: he can connect to the office via pcAnywhere and his 33.6 modem no problem. When he tries to connect to AT & T, he gets a message that there is a RAS error possibly caused by a hardware conflict or that the service provider is busy (which it isn’t). We have already replaced his network stack off a new 95 OSR2 disk, installed DUN 1.3, and the latest AT & T software. Still it won’t work. It makes no sense he can dial in to our pcAnywhere hosts but not to an ISP. Any ideas?
He has a win95 Compaq 166 mhz, 32 MB ram and a 33.6 modem. Thanks