The service was created in 2011 in the Czech Republic. It is an online forum where the users can share their experience with phone numbers, both annoying (mostly telemarketing, surveys) and useful (e.g. couriers, offices)..
Since the beginning, the service has been received very well, which led to localization into more languages. Nowadays, the forum exists in more than 20 languages and 34 countries throughout the world.
The service is intended for anyone who wants to identify the owner of an unknown phone number. The creators of the forum have also recently created the mobile app Call Insider for Android phones. This app, which is connected to the database of the website reverse-lookup.co.uk, also allows users to automatically block telemarketing numbers.
This is a fraud. If you have been victim of a scam by some fraudulent crypto broker, they pretend they can help you claim your money back, but first they need your personal data.
Do not answer and block that number.