This is one of the best videos I have ever seen about voice over IP security, directed towards people with an intermediate level of VoIP security.
Phillip Zimmermann, the creator of Pretty Good Privacy (PGP) and Zfone gives a lecture at the Stanford University Computer Systems department explaining how a voice a over IP call can be intercepted.
Phillip Zimmermann takes some very good questions from Stanford University students an unveils some of the man in middle attacks that can be carried out by snoopers to listen in to VoIP calls.
You can expect the big voyeur agencies conspiring to know everything about you and your family to use some of these tricks.
If you are worried about someone keeping a record of the phone numbers you dial you shouldn’t be using the phone line to make calls, you should be using voice over IP instead, as calls made through VoIP are not included in the data retention laws.
To stop Mi5 buffoon Jonathan Evans and his team from wiretapping your personal calls you can read my past post on Voice over IP security.