True caller can be a joke as some stage

Good day, in regarding blocking spam calls, I have said so before and I shall say it again, the spammers are using truecaller to phone people, at times they are not blocked, I suspect that happens as soon as you RICa, or FICa your SIM card, as some stage they get your phone number, how else can they obtain it? Do they have some sort of agreement to sell your phone number???????? Highly unacceptable and I know that I am not the only one who thinks that