Guardião: The AI That Stops Phone Scams Before Your Phone Ever Rings

Guardian Labs' Guardião blocks phone scams before the call rings or the message is seen. No pop-ups, no alerts, no decisions required from the user. The app is designed primarily to protect elderly and vulnerable populations, and it runs entirely on-device—meaning no call audio, message text, or personal data ever leaves the phone .

The origin story: A €4,000 loss

Founder Rita Barbosa started building Guardião after her grandmother lost €4,000 to a water-filter scam . The experience drove home a painful reality: traditional spam-blocking tools often leave users—especially elderly ones—to spot and avoid scams on their own. Guardião flips that approach: instead of teaching people to distrust calls, the AI distrusts on their behalf .

How the on-device AI works

Guardião acts as an AI interception layer between an incoming call or SMS and the recipient . All AI models run locally on the phone, which means no call audio, message text, or personal data is sent to a remote server .

• For calls: the AI transcribes the conversation in real time, cross-references it against scam databases, and detects manipulation tactics. If a scam is confirmed, the phone never rings .
• For SMS: the AI analyses message content locally and blocks fraudulent messages before they appear in the inbox .
• The interface is deliberately silent: no pop-ups, no alerts, no decisions required from the user. As the company states, "If it is a scam, the phone never rings" .

The system checks known scam information and analyses content for tactics of manipulation . The user never interacts with the blocking layer at all.

Types of scams detected

Guardião is currently trained specifically on Portuguese scam patterns and targets multiple scam categories :

• Impersonation/fear-based scams — e.g., fake water-safety claims, fake official callers posing as utilities or government agencies
• Financial fraud calls — e.g., fake bank or payment requests (one blocked call asked for Multibanco codes)
• Phishing SMS — e.g., fraudulent texts impersonating CTT (Portuguese postal service), banks, or Netflix, often containing malicious links

The system is currently country-specific (Portugal) by design, though expansion to other markets is planned .

False positives vs. false negatives: A deliberate trade-off

The company has not published specific accuracy metrics, false-positive rates, or false-negative rates. However, the product's core design philosophy reveals its strategic tilt: the system is built to block aggressively (minimise false negatives) for elderly users who are unlikely to second-guess a scam . By intercepting before the user sees or hears anything, Guardião accepts that some legitimate calls may be blocked as the trade-off for near-total scam prevention. The company acknowledges this is a deliberate architectural choice for its target demographic .

Business model

Guardião is currently in pre-seed / early-stage. The founder has stated that every euro from a recent prize (Google Gemini API Developer Competition) is going into development . Specific monetisation details—such as subscription fees, carrier partnerships, or B2B licensing—have not been publicly disclosed .

Partnerships

As of August 2026, Guardian Labs has established several notable partnerships :

• Portuguese Public Security Police (PSP) — formal partnership for scam data and reporting, specifically through the PSP's Cybercrime Unit
• Two leading engineering universities in Portugal — research and development collaboration
• One of the country's largest accelerators — programme support
• Support from the President of the Republic of Portugal — public endorsement

The company has also recently partnered with Subvisual, a Portuguese engineering firm, and Invisible Lab to accelerate product development .

Future plans

Guardian Labs plans to expand beyond Portugal into other markets, with the on-device AI architecture designed to be trained on new regional scam patterns without sending data to the cloud . The company hired a Head of Operations in March 2026 and is actively seeking pre-seed funding to scale . The longer-term vision is to make the phone "a safe place again" for elderly populations across multiple countries .