How to block spam calls on iPhone and Android
Most of the useful tools are already on your phone. The rest come with tradeoffs worth understanding first.
iPhone: Silence Unknown Callers
In Settings under Phone, iOS has a “Silence Unknown Callers” option that sends any call from a number not in your contacts, recent calls, or Siri suggestions straight to voicemail without ringing. It's blunt: it also silences legitimate calls like a doctor's office or a delivery driver. Some people leave it off for that reason and rely on carrier-level filtering instead.
Android: built-in caller ID and spam protection
On phones using the Google Phone app, a setting usually called “Caller ID & spam” or “See caller and spam ID” flags likely spam calls automatically and can block them outright. It works by checking incoming numbers against Google's own spam data, not anything specific to this site. Phones running a manufacturer's own dialer instead of Google's may have a differently named but similar feature.
Carrier-level tools
All the major US carriers offer some form of network-level spam labeling or blocking (AT&T Active Armor, T-Mobile Scam Shield, Verizon Call Filter, and similar for smaller carriers). These work before the call reaches your phone at all, which is an advantage over anything running on the device. Check your carrier's app or account settings; some tiers are free and some cost extra for advanced features like reverse number lookup. If you never call outside the US and Canada, also check for an international call-blocking setting; see our guide on area codes that look domestic but aren't for why that matters.
Third-party call-blocking apps
These can catch calls the built-in tools miss, but most of them need access to your contacts and call history to work, and some upload that data to their own servers to build their spam databases. That's a real privacy tradeoff, not a hypothetical one, so it's worth reading what permissions an app actually asks for before installing it. We don't recommend a specific one here for that reason.
Before you block, you can check first
Blocking is permanent and per-device. If you want to see whether a number has already been reported by other people before deciding, you can look it up here first.