Once the software is started, by the very nature of the application there is little protection against abuse. The primary defense is that the participants usually know one another, either personally or professionally. Opening up a shared application with a stranger on the Internet is an invitation for abuse. He or she could look at or even obtain copies of files before the other party realizes what is happening and closes the connection. Video and audio connections that are made directly to another person's system, whether via ISDN or LAN, are not any more of a privacy concern than making or accepting a phone call.
Most cameras have a shutter that enables the user to temporarily block video transmission.
Some software also has a method to turn video transmission on and off at will. This allows the recipient of a video call to identify the caller before allowing him or her to view the recipient's video. Some desktop LAN-based software makes use of an intermediate server as a sort of directory of systems that are available for audio and video conferencing. NetMeeting offers both a central connection service and the ability to make a direct connection. The installation default, however, is to list a person's system and their email address on their central service.