Dial up accounts are not considered a "dedicated" or 24 hour, 7 day a week connection.  Customers are expected to disconnect when not actively at their computer.  The following time limitations apply:

8 hour continuous session - after 8 hours of being continuously dialed in, the server will drop the connection.  You can dial right back in.

30 minute idle disconnect - if you are idle, meaning doing nothing over the Internet connection, the server will drop the connection.  You can dial right back in.