RICA is not Private

These days you have to RICA your SIM card otherwise it is useless. So you RICA, thinking that your number is private only to your service provider. But no, it is not. I receive so many phone calls from different service providers and other companies and as soon as you ask where they got your number, they state from a database and stating that if you RICA your number your name is added to this database. Could someone please clarify this to me?