Do Phone apps such as TrueCaller keep a blacklist of blocked numbers

[coo1guy]

Here in Switzerland, I receive quite some unwanted commercial calls from insurance companies typically.

I've been using Android's default Phone app for a while and blocked numbers and marked them as spam.
Then, I installed TrueCaller.
I'm wondering if blocking numbers and marking them as spam contributes to some sort of blacklist that could benefit to everyone by blocking numbers marked by a certain number of people as spam or if no such shared centralized information exists.

By the way, if an app where blocking and marking as spam was shared among users, I'd be interested.

Thanks

 

[Dannydet]

That's what True caller does, if you mark it as spam, it will add it to the list of spam callers globally.