HSBC, Lloyds Bank, Santander, TSB, Nationwide Building Society and Virgin Money may be leaving customers vulnerable to fraudulent spoofing attempts, a Which? investigation has suggested.
Spoofing, where fraudsters impersonate legitimate companies, is a common tactic used to deceive victims. Scammers forge the name or number that comes up on an email, phone call or text so it appears to match that of a genuine firm.
To make it harder for fraudsters to impersonate them, companies can sign up to regulator Ofcom's Do Not Originate (DNO) list - a shared resource with telecoms providers to help them identify and block calls likely to be spoofed.
