Facebook has launched a new caller ID-type app for Android users that uses data from Facebook to tell you who is calling and will help you block unwanted calls. The app called Hello matches phone numbers of incoming and outgoing calls to Facebook profiles to show you who you are talking to.

It also blocks calls from commonly blocked numbers and searches for businesses to call, CNET.com reported.

The feature will only work if the caller has shared his number with Facebook and if you would normally be able to see that information. For example, if you share your number publicly, people with Hello downloaded will know it is you calling even if they do not have you as a contact.

Currently, Facebook is rolling out Hello for public testing in the US, Brazil and Nigeria. The app is available as a free download in the Google Play store.

This is how it works. Once downloaded, you sign in with Facebook, and give it permissions to sync your contacts with Facebook and interact with calls.

When a user gets a call, the app – built by Facebook’s Messenger team – shows information about who’s calling, even if that number is not saved in that user’s phone.

However, it will only show information that people have already shared with the user (or publicly) on Facebook.

Hello lets you ‘block’ specific numbers which means they get sent directly to voice mail. One can use it to search for people and businesses on Facebook and call them with just one tap. The app also promotes the use of free calling over Wi-Fi, something that has long been a part of Messenger.

With permission, Hello will add profile pictures and other information to the contacts in your address book.

It can also serve as an enhanced version of your phone book, with extra information about friends and others shown inline as you scroll through contacts. Hello works and looks quite similar to caller ID app TrueCaller.