Inside an unmarked building in a Manila business district, a war is being waged 24/7 against dark and mostly hidden crimes — the online sexual abuse and exploitation of children.

Here, a system developed by cybersecurity experts at PLDT — the Philippines' largest telecommunications company — is blocking millions of attempts by subscribers to access child sexual abuse material every day.

Since last November, PLDT has blocked more than 1.3 billion attempts to access such material with its pioneering child protection platform, a system that checks user searches against a vault of known web addresses hosting sexually abusive content.