Call screening

Call screening is the bucket of features that filter incoming phone calls — silencing spam, intercepting robocalls, asking unknown callers to identify themselves, or sending suspected fraud directly to voicemail. Both phone OS makers and carriers offer call-screening features; most are free, some are subscription tiers.

OS-level options

• iPhone "Silence Unknown Callers": Settings → Phone → Silence Unknown Callers. Numbers not in your contacts go straight to voicemail. Simple but blunt — you can miss legitimate calls (deliveries, doctor's offices, schools).
• Pixel Call Screen: Google's on-device AI answers unknown calls, asks the caller to identify themselves, transcribes the conversation in real time, and lets you decide whether to pick up. Pixel 6 and later. Works with Google Fi and most US carriers.
• Samsung Smart Call: identifies known spam patterns and labels calls in your call log. Works on Galaxy phones globally.

Carrier-level options

• T-Mobile Scam Shield: free with all postpaid plans. Identifies suspected spam, blocks known robocallers. Premium tier ($4/month) adds reverse number lookup and voicemail-to-text.
• Verizon Call Filter: free version blocks high-risk spam; premium ($3/month) adds caller ID lookup, personal block lists, neighborhood spoof protection.
• AT&T ActiveArmor: free version blocks suspected fraud; advanced ($4/month) adds caller ID and reverse number lookup.
• Visible/Mint Mobile/etc.: generally rely on the underlying carrier's spam blocking but don't offer separate apps. Use OS-level features instead.

STIR/SHAKEN and the broader picture

The FCC mandated all major US carriers implement STIR/SHAKEN (a call-authentication framework) starting 2021. The phone network now stamps a verification status on each call — "verified," "partially verified," or "unverified." The "Spam Likely" or "Scam Likely" labels you see in caller ID are largely driven by this framework. Robocall volume in the US dropped meaningfully after STIR/SHAKEN deployment, though not eliminated. Most call-screening features layer on top of these stamps to make the verdict actionable.

Practical setup for most users: enable your phone's OS-level screening (Silence Unknown Callers on iPhone, Call Screen on Pixel) plus your carrier's free spam blocking. Don't pay for premium tiers unless you have a specific reason — the free options catch most modern spam.