Thanks - factual is fine So My Friends in the Met could have a few of these things at sensitive points, and sit there and collect data along the lines of name

Thanks - factual is fine So My Friends in the Met could have a few of these things at sensitive points, and sit there and collect data along the lines of name (via phone number), time, date, location, device ID. Running this for some weeks would allow them to build up a list of people traversing a certain route daily. Phone/sms could they decrypt the phone calls with the device ID? Seems a lot of data to collect given the number of people passing through many locations in central London.