TalkTalk claims to be the first major UK internet service provider to allow broadband customers to block malicious or offensive material at server level.
TalkTalk's Home Safe, which enables parental blocking controls, sits between the web and broadband users, scanning sites and putting malware-free sites on a "white list" for 24 hours.
TalkTalk says the system blocks adverts on web pages linked to malicious content, while the user accesses the rest of that page.
But security professionals have questioned whether the service will be able to react fast enough to new threats, according to the BBC.
Some believe the 24-hour all-clear white list might not work for larger sites like Facebook that are frequently targeted by cyber criminals. Analysts say tech-savvy teenagers may be able to circumvent parental controls.
TalkTalk said the system was the most robust available, but its filters were not intended as a cure-all or as a substitute for good parenting.