You'll be using this PC to attempt connections to the modems you've found, so it should have any software you wish to try. On my first scan, I was surprised to find several modems that answered a call placed by the remote control software that we use, but didn't prompt for a password. One was an administrator, logged in to the network with the Administrator account. My choice during this first scan was to protect the identities of those users, but to immediately implement authentication and verify that it was working properly. So I approached the offenders one by one to explain my findings and the changes that were required, and found everyone to be cooperative.
Recommendations Define strict policy with associated punishment .
A policy of registering all modems with the security staff will help to ensure that modems are set up properly the first time, instead of only when they are found by your scans. Verify the need for every modem . As an 'insider' you have some advantages, and you should use them. After you've completed your scan and closed the obvious holes, take the report provided by your phone administrator and contact everyone that has a modem, even if they didn't show up in the scan. In my experience, a large percentage of users had either inherited the PC from someone else and didn't use the modem, or no longer performed the functions that had required it.