Re: Dunce Cap tip
One of the banks I've dealing with even phones you up from a mobile phone number. I've no idea if there is some business system that does this or if it's staff doing BYOD to call customers.
Either way I'd suggest that it doesn't fill a cynical customer with joy to get a call from a random 07... number stating it's my bank and asking for security information. Then making it a PITA to call you back by hiding your contact numbers and making your contact system a Sisyphean nightmare.