Corta Spam: Call Blocker

Corta Spam is your phone app. It replaces the default dialer, receives every incoming call, and screens it against rules you write yourself, before your phone rings.

No ads. No tracking. No accounts. No network access at all — every rule and every log entry stays in a database on your device, and the app has no code that could send it anywhere.

WHEN A CALL COMES IN

Corta Spam is the app that rings. It shows the caller full-screen with Answer and Decline, over the lock screen when your phone is locked, and names the caller from your contacts. While you are on a call you can leave the app and get back to it from the notification.

WHAT YOU CAN BLOCK

• Specific numbers — with a label so your call log tells you why
• Patterns — block a whole range with wildcards, like +34900* or *1234
• Countries — block a dialling code you never expect a call from
• Quiet hours — silence everything on a schedule, except your allowlist
• Repeat callers — block a number after it tries too many times in a short window
• A bundled spam list — known scam dialling codes, shipped inside the app

Your contacts and your allowlist always come through, and a number you block manually stays blocked even if it is in your contacts. You decide what wins.

WHAT HAPPENS TO A BLOCKED CALL

Your phone stays silent. The call log records what happened and which rule made the decision, in your language. You can call back or copy any number straight from the log.

You choose what happens to a number no rule matched: let it through, block it, or let it through but flag it for review. There is also an optional setting to let an unknown number through once it has tried several times — because a real person calling repeatedly is usually not a robocall.

PRIVACY

The app requests no access to your system call log, SMS, storage, location or camera. It reads your contacts only to recognise callers you know, and that never leaves the device. The microphone is requested only if you switch auto-responder recording on, which ships off; recordings stay in the app's private storage and are never transmitted.

There is no analytics SDK and no crash-reporting SDK. The full privacy policy is published alongside the source code, and you can check every claim in it against the code.

OPEN SOURCE

Every line is public and auditable at github.com/cpinan/Corta-Spam, under the MIT licence.

LANGUAGES

English, Spanish, Portuguese and Hindi.

NOTE ON PERMISSIONS

Corta Spam is a phone app, so it must be set as your default phone app. That is the only way Android lets an app receive a call, show it, and screen it before it rings — it is how the app works, not an extra request.

For the same reason it shows the incoming call full-screen over the lock screen, the way any phone app does. Without that, a call arriving while your phone is locked could not be answered.

The auto-responder is experimental. It answers a blocked call and plays a greeting, but on modern Android the caller may not hear it clearly; treat it as a bonus, not a feature to rely on. It can optionally record the message a caller leaves — to turn that on, your own greeting must contain a line telling the caller they are being recorded.

Recent changes:
Do Not Disturb is now honoured while a call is ringing. The auto-responder mutes itself once the greeting finishes, so it can't keep recording past that point.

New: a one-tap "hang up & block" action on the call screen.

Fixed: a call-log dialog that reopened on its own, a dial pad number that retyped itself after switching tabs, and text that showed a raw "%d" instead of a number.