That wouldn't be it. There are options to keep the TCP/IP stack loaded 100% of the time, and there are PPP options to connect only when needed. Now if the TCP/IP stack is on 100% of the time and/or PPP is set to *NOT* connect only when needed, you will get your machine trying to dial into the internet when you turn it on under MacOS 9.
However, without knowing if he is referring to a modem or not, I cannot say this is his/her exact problem.