There has been a growing number of reports from people who have received an automated phone call which states that their National Insurance number has been “compromised”. The recipients are then instructed to “press one on their handset to be connected to the caller”, which will allegedly fix the problem and even be issued a new National Insurance number.
https://www.scotsman.com/read-this/national-insurance-number-phone-call-scam-has-been-reported-uk-what-look-3113031