That's the title used for a Register article warning about scammers using the UK track and trace program. If you're in the UK and get a call from someone claiming to be contacting you regarding the T&T program then it seems thetre is no way at present you can verify they are who they say they are.
Easy for me to say, but my advice would be to not believe anyone who calls up making that claim. I know of no solution to the problem right now.
So, if anyone from the UK is reading this - I hope it's been useful.
* edit *
Having considered this a little more (I know, 'shooting' from the hip is dumb, but sometimes I just get the urge to write) possibly the best approach if anyone DOES receive a call will be to ask where and when they were nearby the infected person. While far from foolproof, it will at least give an indication of whether the caller is genuine and working from real data.
And NEVER give them useful personal information such as date of birth, national health number or national insurance number etc, let alone any kind of financial information. If they have access to computer records of your phone number and address then they have access to those things too, if they need them.