I just had a phone call - it comes up "International", so I'm immediately wary, as I get a lot of such calls which are silent. I think it's a system where lots of numbers are rung simultaneously, and those that are answered eventually have an operator speak to them. I usually put the phone down before that can happen.
This one was from a firm in Switzerland, who wanted to sell me some Google Adwords marketing. (I already use, and pay for Google Adwords for my websites, and use my own control panel), so it's already got my back up. I asked him for his phone number - but he said he wasn't allowed to divulge that. (Also gets my back up). I was quite civil with him, but explained that I didn't fall for scams (which got
his back up).
I left it at that, but felt guilty afterwards - I always do. Why should I feel guilty? I didn't request the bloody call...