How NoCall works: community spam database and on-device call protection
NoCall is a website and a mobile app that help you find out who is behind an unknown number and stop unwanted calls. It is built on a community database: people report the numbers that call them with telemarketing, scams, debt collection and other unwanted calls.
Today the community database holds 283,600 numbers flagged as spam, backed by 144,834 community reports. This guide explains how that data is collected, how you can check a number, and how the app uses the same data on your phone.
A database built by the community
Every number in NoCall comes from people who received a call and reported it. A report says which kind of call it was and can include a comment describing what happened.
Reports are reviewed before they are added to the public database, and comments are published once they are approved. The more people report the same number, the clearer the picture becomes for everyone else.
Check any number on the web or in the app
Type a number into the search box on nocall.io or in the app. If the community has reported it, its page shows the main category, a risk level, the reports and the comments left by other people.
Searching on the website is free and works in any browser, so you can check a number from a computer before you call it back.
Protection on your phone
The app downloads the spam database to your phone. When a call comes in, the phone checks the number against that local copy, so the check works even without an internet connection.
- iPhone: NoCall uses an Apple Call Blocking & Identification extension (CallKit). Known spam numbers are labelled on the incoming-call screen, and with Pro they can be blocked automatically. A separate SMS filter can move texts from reported numbers to the Junk folder.
- Android: You choose NoCall as your Caller ID & spam app. It checks each incoming call against the on-device database and warns you while a reported number is calling; with Pro it can reject those calls automatically.
Keeping the database up to date
The first sync downloads the full list; later syncs only fetch what is new. On the Free plan you sync manually from the app. Pro adds daily, weekly or automatic background sync, and you can limit syncing to Wi-Fi.
Who NoCall is for
- Constant sales calls: People who receive telemarketing calls every day and want to know who is calling before they answer.
- Fraud and smishing: Anyone who wants to spot phone scams and fraudulent texts before they fall for them.
- Privacy first: Users who prefer a protection that checks calls on the phone itself instead of sending every incoming number to a server.
Get NoCall
Identify spam calls before you answer, with a database of 283,600 numbers reported by the community.