It recognised a regular at “hello” and then forgot them. A customer would be greeted by name, and three sentences later be asked for the phone number they were ringing from. Your receptionist was working out who it was talking to from each individual sentence, so the moment somebody said something short like “use my account”, there was nothing in that sentence to recognise them by.
Now it settles that once and keeps it. Details you already hold are used instead of being asked for, which also removes the most error-prone thing on any call — a customer spelling an email address down a phone line.
Being recognised still is not proof of identity. Anything that creates a booking, a refund or an escalation still sends a six-digit code to the email on file and waits for it to be read back, exactly as before. Recognising somebody saves them repeating themselves; it does not unlock their account. You can switch that verification off per request type if you want to, but it is on by default.