Anatel, Brazil's telecom regulator, has set rules for the anti-spam call-blocking systems offered by phone carriers, responding to complaints from at least seven companies against Vivo Anti-Spam, a tool they say blocked thousands of legitimate calls since June. The decision was formalized in Despacho Decisório No. 82/2026, a board-level ruling, according to Canaltech, and has the backing of the Ministry of Communications and the Ministry of Justice and Public Security, the agency told G1.
Under the new rules, blocking systems must combine criteria such as call volume, average call duration and completion rate. Call volume alone cannot justify a block: carriers will have to distinguish customers making many legitimate calls from those showing potentially abusive behavior. Decisions must respect the principles of proportionality and non-discrimination.
Offering the service is optional for carriers, but those that do must switch it on by default for all customers at no extra cost. Consumers must be told in advance how the tool works and may turn it off at any time, through a free process the carrier has up to 24 hours to complete, according to Canaltech. The rules bar blocking numbers belonging to essential services, such as health agencies, security forces, Civil Defense, firefighters and suicide prevention hotlines. Carriers must keep channels for challenging blocks, with a general deadline of ten calendar days to respond; requests from public agencies and health or emergency services must be assessed within six hours. Companies will also have seven days to report to Anatel the blocking criteria and periods they adopt.
The dispute behind the rule
Vivo Anti-Spam, which promises to identify and block mass and fraudulent calls before they reach the customer, triggered a dispute among carriers at Anatel in June. According to G1, one complaining company said more than 16,000 calls, including calls from hospitals and public agencies, were cut off by the tool. Another reported the blocking of more than 800 numbers belonging to a city hall in the interior of São Paulo state. Carriers also said the system blocked numbers authenticated by Origem Verificada, a verification system created by the industry to fight unwanted calls.
Vivo denied having stopped calls that follow the rules of its anti-spam system and of Origem Verificada. "Only companies making mass calls without identification will be blocked," the carrier told G1 in June, adding that it is working to fight number spoofing received through interconnection from other networks. According to data from Telefônica Brasil, Vivo's parent company, presented in the proceedings, only 0.02% of users asked to deactivate the service in its first two months, and Anatel's specialized federal prosecutor's office concluded that automatic activation, as long as an opt-out exists, does not violate consumers' right to choose.
In practice, the rule draws the line for both sides of the business. For companies that depend on the phone to reach customers, from banks and collection agencies to city halls and hospitals, there is now a formal challenge channel with a defined deadline, something that did not exist when the blocking began. For consumers, the filter against abusive calls becomes a free, standardized service that can be switched off at any time.