In cases such as this, you might be able to recognize the employee or at least the department they work for. A traceroute may also show where within the company the person works. For Cable, DSL and dedicated circuits, the POP will be explicitly defined and always at the same location day after day. An IP number is allocated to the user for the duration of an online session. When the session ends, the IP number is re-assigned to subsequent users.
Many Internet providers keep a log of dial-up user activity.
Some ISPs will also have caller ID enabled on their modem ports, so they may also have the phone number you dialed in from. Some companies are providing internet access for free. Internet users may have these kinds of accounts as their main account, or as a back-up account. Since there is no payment being given for these services, it may be easier for people to assume a false identity when registering for this form of access. There are numerous other ways for users to access the Internet anonymously, such as walk-up terminals at public libraries or airport terminals.