My record for keeping one of these scammers on the telephone is approaching 25 minutes! I was not busy and I hate both the cold calling and the fact that they are not even offering a decent product but frightening the gullible and unwary into purchasing rubbish 'security' software.
The call in question I pretended that i couldn't understand what she was saying and made her spell everything she asked me to type. When we finally got to the part where she asked me to log on to a particular website I told her I couldn't do that because they were a bunch of scammers.
The girl was obviously under training because a male interrupted and started shouting abuse and threatening to 'come and f*** my mother/sister/wife'. He was apoplectic with rage. It didn't help that his ranting caused me to start laughing and still makes me smile with satisfaction some weeks later.