Three steps, about a minute
CallSift needs one thing to work: Android has to know that it is your call screening app. Nothing else — no contacts permission, no microphone, no account.
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Install and open the app
Requires Android 10 or later.
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Set CallSift as your screening app
Follow the prompt on the Settings tab and confirm. Android will ask you to replace whatever is screening calls today — on Samsung phones that is usually Smart Call.
To do it by hand:
Settings → Apps → Default apps → Caller ID & spam app. The exact wording varies a little by manufacturer. -
Check your home country
CallSift reads the country from your SIM and registers it for you. If you regularly take calls from another country, add it — see Home countries.
Four screens, nothing hidden
CallSift is four tabs, and everything the app knows is visible in them.
| Tab | What it's for |
|---|---|
| Log | Every call the app has judged, newest first, marked Allowed or Blocked with the reason. Tap an entry to copy the number and look it up in your browser; long-press to put it straight onto a list. Clear log empties it. |
| Lists | Your whitelist (always allow) and blacklist (always block). Type a number and tap Add; long-press an entry to delete it. |
| Prefix | Rules that match the beginning of a number instead of the whole thing — a whole area code, or the range a spam operation is calling from. |
| Settings | Protection status, the four basic switches, home countries, and screening of unknown numbers. |
How a call is judged
When a call arrives, Android hands the number to CallSift before the phone rings. CallSift walks down this list and stops at the first rule that matches. If nothing matches, the call rings normally.
- No caller IDThe caller has withheld their number.Blocked, if enabled
- On your whitelistA number you have explicitly trusted.Rings
- On your blacklistA number you have explicitly refused.Blocked
- Outside your home countriesThe number belongs to a country you haven't registered.Blocked, if enabled
- Matches a blocking prefixThe number starts with a range you have refused.Blocked
- Matches an allowing prefixThe number starts with a range you have trusted.Rings
- Screening unknown numbersA number not on any list, calling for the first time.Held (see below)
- Nothing matchedThe default is to trust the caller.Rings
Numbers are normalised to international format before any of this happens, so 090-1234-5678 and +819012345678 are recognised as the same caller. Emergency and short service numbers are always let through.
Screening unknown numbers
This is the part no list can do for you. Auto-diallers and one-ring scams work by volume: they call once and move on. A person with real business calls again.
So CallSift holds the first call from a number it has never seen, and lets the next one through. Nothing is permanently blocked — the caller is simply asked, without knowing it, to prove they meant it. Contacts are never affected.
Three modes
| Mode | What happens to the first call |
|---|---|
| OFF (no screening) | Unknown numbers ring like any other. Turn screening on when you're ready for it. |
| Silent | The first call rings silently — you miss nothing, because it still appears in your call log and in CallSift's log, and you can call back. The gentlest setting. |
| Strict | The first call is rejected outright, exactly like a blacklisted number. The strongest setting. |
Three timings
| Setting | Default | What it means |
|---|---|---|
| Calls to hold | 1 time | How many calls from a new number are held before it rings through. Raise it if you get persistent spam. |
| Call-back window | 10 min | How long the caller has to try again for it to count as a call-back. |
| Remember approved numbers for | 30 days | Once a number has been let through, it rings straight away for this long without being screened again. |
You can watch the whole sequence happen in the Log: Awaiting call-back (attempt 1) … then Called back — approved.
Home countries
Most people never receive a legitimate call from abroad. A great deal of phone fraud arrives from exactly there.
CallSift detects your country from your SIM and registers it as your home country. With Block calls from outside my home countries switched on, calls from numbers belonging to any other country are stopped before they ring. If you have family, colleagues or customers overseas, register those countries too — add as many as you need, and calls from them are treated exactly like domestic ones.
Country identification is done on the phone using an offline number database. No lookup leaves your device. If a number is malformed, CallSift falls back to reading its country code; if it still can't tell, it errs on the side of letting the call through.
Whitelist & blacklist
The whitelist beats everything below it: a number there always rings, even from outside your home countries. The blacklist stops a number for good.
The quickest way to build both is from the Log — long-press a call you recognise and choose the list it belongs on. You never have to retype a number you've already received. Long-press an entry in the Lists tab to remove it.
Not sure who a number belongs to? Tap it in the Log: the number is copied and opens in your browser as a search, so you can check it against caller-report sites before deciding which list it deserves.
Prefix rules
A prefix rule matches the start of a number instead of the whole thing, so one rule can cover an entire range — a toll-free block, a city code, a range a call centre is dialling from.
- Starting with
+— matched against the international form, e.g.+1212. - Starting with a digit — matched against the domestic form, e.g.
0120.
Each rule is either Allow or Block. When two rules could apply, the longest prefix wins, and where two rules are the same length, Block beats Allow. So you can block 03 broadly and still let a specific 0312 range through.
Settings reference
The four switches under Basic settings:
| Switch | What it does |
|---|---|
| Block calls from outside my home countries | Rejects any number belonging to a country you haven't registered. The single most effective setting against international fraud. |
| Block calls with no caller ID | Rejects calls where the number is withheld. Off unless you turn it on, because some legitimate callers — hospitals, some offices — withhold by default. |
| Show a notification when a call is blocked | Tells you a call was stopped, so nothing happens silently behind your back. |
| Keep blocked calls in the phone's call history | Blocked calls stay in your normal call history, so you can always see who tried. |
At the bottom of the Settings tab, Open the user guide (callsift.app) brings you back to this page whenever you need it.
What the caller hears
A blocked call is never connected, so there's no ringing, no voicemail, and no beep that announces they've been blocked. They hear the standard network message — the same one they'd get if your phone were switched off or out of range.
That matters more than it sounds. A blocker that announces itself confirms to a spam operation that your number is live and worth passing on. CallSift tells them nothing.
On your side nothing is hidden: you get a notification, the call stays in your call history, and the reason is recorded in the Log.
Nothing leaves your phone
Every decision described on this page is made on your device. There's no server to consult, no account to create, and no analytics or advertising code in the app.
- Your lists, prefix rules and log live in a database on the phone itself.
- The app does not read your contacts. It doesn't need to — Android never asks it about a saved contact in the first place.
- Country identification uses an offline database bundled with the app.
- Uninstalling deletes all of it. There is no copy anywhere else.
The full policy is on the Privacy Policy page.
Common questions
How do I find out who called?
Tap the entry in the Log. The number is copied and searched in your own browser — caller-report sites usually tell you within seconds who it belongs to. The search starts only when you tap and runs in your browser; the app itself has no internet access.
Will it block calls I actually want?
Numbers in your contacts always ring — Android doesn't even show them to the app. Beyond that, screening of unknown numbers is OFF until you turn it on, and anything that isn't from an unregistered country or on your blacklist rings normally.
Does it work while the app is closed?
Yes. Android calls CallSift itself whenever a call arrives. You don't need to keep it open or running in the background.
Can it record or answer calls?
No. Android doesn't allow an app to do either, and CallSift doesn't request the permissions that would come close. It decides on the number alone, before the call connects.
Is there an iPhone version?
No, and there can't be. iOS has no equivalent of the screening interface CallSift is built on — an iPhone app can only hand over a fixed list of numbers in advance, which rules out screening unknown numbers entirely.
Subscription? Ads?
Neither. CallSift is bought once and is yours. No subscription, no advertising, no in-app purchases, no limit on how many calls it screens.
I changed phones. Do my lists come with me?
Not automatically — the data only ever existed on the old phone, so there's no cloud copy to restore from. That's the trade-off that comes with collecting nothing.