|  |  | Most administrators feel their dial-up servers are secure since no one outside the company knows their phone numbers. That is where information gathering and wardialers come in. Hackers find the voice numbers to the company. Chances are the dial-up numbers start with the same prefixes. Some companies even put voice numbers on their Web page. Hackers can also get numbers from phone books or other information sources. Hackers can check the name and number registered with the InterNIC. The number listed is probably the Network Operations Center (NOC), and is often where the modems are usually located.