Key personnel must be educated, persuaded, and regularly reminded about being discreet in public and on the telephone. Misunderstandings persist about the vulnerability of telephone lines to taps. The security department should prepare an article on telephone security for inclusion in the company newsletter. Another element of an effective defense against eavesdropping is the provision of secure areas for personnel to use for sensitive discussions. Secure rooms are sparsely furnished and positioned in the interior of the building. This location makes the use of an eavesdropping transmitter difficult because of the many barriers through which its signal must pass to reach a reception point outside the building. These secure areas can be protected against audio penetration through the proper application of physical barriers and access controls. Secure rooms should be kept locked, with only one person controlling access. The use of detection devices is essential. Such devices should take into account the eavesdropper's purpose. Since a bug is only likely to be used when the room is occupied, this is the time when the bug-detection operation should be performed.