Overseas call centre, several seconds to cut in on their side. They assumed my name was 'David' but when I said 'that's not my name' they were quite pushy asking for my full name and other details. Seems like a phishing scam - if they can get your full name, they can then piece together other details and change things like your phone contract or bank details.

DO NOT CONFIRM YOUR DETAILS EVER ON RANDOM PHONE CALLS.