If you have the same experience as I do, you will find that someone is hacking your settings in your control panel from time to time. These appear to be random acts of sabotage.

I have found my settings for things like caller id changed for no reason. Maybe you have to.

It isn't so much that no one knows how it is happening, but that the system is so buggy that no one can lock anything down at all. My best suggestion is to check your settings often and listen to your correspondents when they say they found something wrong when receiving your calls or calling you. They probably are right.

The bottom line is to always be vigilant.