Fraudsters might pretend to be your bank, HMRC, the police, BT or another trusted institution. They contact you via telephone, SMS or email and attempt to convince you to send money to an account that they control.
Just because the number matches a number you trust, it doesn’t necessarily mean it’s them contacting you. Fraudsters are able to ‘spoof’ those organisations’ telephone numbers, so when you receive the call or SMS you believe it’s legitimate. It’s important to be aware that ‘spoofing’ is easily done.