STIR/SHAKEN in Brazil: what it is, Anatel's deadlines and what changes for companies that call

I bet you didn't pick up the last unknown number that called you.

Nobody does. And nobody is wrong.

Brazilians didn't stop answering the phone. They stopped answering strangers. It became a survival rule, and the bill landed on everyone with a good reason to call. The clinic confirming an appointment. The bank flagging a due date. The real estate agency following up on a showing.

That rule is about to be turned on its head. And the companies that understand it first will be the first to get answered again.

What is STIR/SHAKEN

STIR/SHAKEN is the pair of protocols that guarantees the number shown on the screen really belongs to whoever is calling.

• STIR stands for Secure Telephone Identity Revisited. It's the specification for the digital certificate that travels with the call.
• SHAKEN stands for Signature-based Handling of Asserted information using toKENs. It's the set of rules that defines how carriers apply and verify that certificate.

The closest analogy is the padlock in your browser. Just as the certificate proves a website is legitimate, STIR/SHAKEN proves the call came from a legitimate number.

The target is spoofing, the faking of caller ID. And spoofing is far older than any recent technology. It exists because, for decades, calling someone never required proving who you were. The number on the screen was a suggestion, not a fact.

What is Origem Verificada

Origem Verificada (Verified Origin) is the name of Brazil's STIR/SHAKEN implementation, according to the official page of Anatel, Brazil's telecom regulator.

It's run by ABR Telecom, which acts as the Identification and Authentication Authority (AIA), the central body that issues and validates the certificates carriers use. More than 320 providers have already joined the system.

Beyond the signature, Brazil is rolling out RCD (Rich Call Data), which shows on the phone screen:

• The name of the company calling
• The brand's logo
• The reason for the call

It works on 4G and 5G phones with VoLTE turned on. In practice, it's the difference between "unknown number" and "São Lucas Clinic, appointment confirmation".

What changes in answer rates

This is the most important effect of the change. And the least talked about.

Brasilseg, an insurer that added brand identification to its outbound calls, reported three times more calls answered compared with unidentified calls, according to a report by Consumidor Moderno.

Three times. Hold on to that number.

Now take it to healthcare, where no-shows eat up 10% to 30% of the schedule and more than half of them come down to simply forgetting. A confirmation call only works if it gets answered. With the clinic's name on the screen, the patient picks up, confirms or reschedules. The full math is in how to reduce appointment no-shows.

The same goes for a scheduled exam, a result that's ready, a delivery to arrange and a payment to negotiate. Useful calls that were stuck behind a wall of distrust.

What Anatel's regulations say

Deadlines: who needs to authenticate and when

The first phase covers about 350 companies, responsible for roughly half of Brazil's phone traffic, according to Sigatel.

What happens to companies that don't authenticate

The process escalates and ends in a block. The carrier monitors each customer's volume, notifies anyone out of compliance, grants 30 days to fix it and, if nothing changes, blocks outbound calling.

Carriers also send Anatel a report by the 15th of each month listing authenticated users, notifications, blocks and exemption requests, as reported by TELETIME. Some flexibility is planned for public services, essential services and customer service that isn't mass calling.

The three attestation levels

In the United States, C-attested calls carry 8.4% robocalls, versus 1.9% for A attestation, according to TransNexus. Carriers use that history to decide whether to deliver, flag or block.

In practice, attestation level has become number reputation.

Call authentication in Brazil, by the numbers

• The country handles about 30 billion calls per month
• Roughly 6 billion are authenticated today, less than 20% of the total
• Authentication and blocking have already stopped more than 90 billion unwanted calls
• Only four countries have systems like this in rollout: the United States, Canada, France and Brazil

The data comes from ABR Telecom, in an interview with TELETIME.

Notice the compounding effect. As anonymous traffic shrinks, an identified call becomes more valuable. Less noise on the screen, more attention for those with a name.

What the United States has already shown

The US rolled out STIR/SHAKEN between 2019 and 2021. In June 2026, according to TransNexus, 48.8% of calls arrived signed at their destination, and robocalls made up 3.5% of signed calls.

The lesson for Brazil is about pace. Authentication isn't a switch, it's a journey of several years. And it rewards those who start early, because number reputation is built on track record.

How to put your company's name on the call

The feature is called Rich Call Data, also known as enhanced caller ID or branded calling. It's what shows the name, logo and reason for the call on the recipient's screen.

For your name to appear, four things need to be in place. The call has to go out authenticated. Ownership of the numbers has to be proven. The business name, logo and call reasons have to be submitted to the carrier's specifications. And everything has to be approved and tested on 4G or 5G phones with VoLTE.

Sounds like a lot. It is, if you try to do it yourself, one carrier at a time.

At Vozis, we own that path. Our agents' calls go out authenticated through the certified carriers we operate with, and our team handles the numbers, the visual identity and the testing until your brand shows up on the customer's screen. You never have to talk to a single carrier.

How to improve your call answer rate

Identification solves half the problem. The other half is dialing behavior, and carriers measure it all the time.

The most common mistake is treating answer rate as a volume problem. It's a reputation problem. And reputation is built on identity and consistency.

That's what Vozis takes care of in every operation:

• Number reputation. High attestation, volume spread across numbers with a track record and no dialing the same person ten times in one day
• The right time. Cadence respects time of day and context, and the second attempt moves to a different window, because whoever doesn't answer in the morning picks up at the end of the day
• A real reason. Confirmations, notices, follow-ups and open issues get answered. Generic offers don't, and we never put an agent on the phone without a reason to call
• The conversation after hello. A bad call teaches the customer not to answer next time. A good conversation teaches the opposite

What the certificate doesn't solve

STIR/SHAKEN authenticates the number, not the conversation.

The certificate proves the origin and puts your brand on the screen. It doesn't make the call relevant, and it doesn't guarantee the person will keep listening past the third second.

By 2028, every company will have a certificate. It stops being a differentiator and becomes table stakes, like the padlock in your browser. What will set one company apart from another is the quality of the conversation that follows the pickup.

And that's where AI voice changes the game. An AI voice agent runs the entire call as a conversation, with no menu and no rigid script, and resolves the issue within the call itself. The difference from IVR and the cost per contact are in replacing IVR with AI voice.

A certificate without a good conversation is an open door to an empty room. A good conversation without a certificate is someone brilliant talking from a number nobody answers.

Vozis delivers both halves.

Why companies choose Vozis to make identified calls

From certificate to first hello

Most vendors deliver one piece. One provides the line, another the dialer, another the AI. At Vozis, authentication, on-screen identity and conversation are part of the same operation, with one team accountable for the entire result.

Reputation that grows over time

A well-managed number gets answered more every month. Vozis tracks delivery and answer rates for every number and adjusts cadence before the carrier flags it as spam.

A conversation the customer wants to have

An ultra-realistic voice in native Brazilian Portuguese, with no menu and nothing robotic about it. The customer picks up because they saw your name. They stay on the line because the conversation is worth it.

An operation, not a tool

You don't need to understand attestation, VoLTE or certificates. Vozis handles the rules, the numbers, the integration with your systems and ongoing optimization, with dedicated management.

Who Vozis is right for

Companies with a legitimate reason to call. Confirming an appointment, sharing a result, picking up a stalled conversation, resolving something the customer wants resolved. Healthcare, real estate, finance and collections are where we operate most.

And it's not right for anyone who wants to call with nothing to say. If the call doesn't solve anything for the person who answers, it shouldn't happen, and no technology can fix that.

A good call isn't the one that pushes hardest. It's the one that was expected.

What about the 0303 prefix?

The 0303 prefix was created to identify outbound telemarketing calls in Brazil. In August 2025, Anatel decided to end the requirement, betting on authentication as a more effective replacement.

Brazil's Federal Public Prosecutor's Office recommended reinstating the prefix, arguing that it gives consumers visible, immediate identification.

The debate is still open, and it comes down to two philosophies. Identify by prefix, which is visible, or authenticate by certificate, which is verifiable.

Frequently asked questions

Is STIR/SHAKEN mandatory in Brazil?
Yes. Since November 15, 2025, it has been mandatory for companies that originate more than 500,000 calls per month per provider and per service. By October 31, 2028, the requirement extends to all domestic phone traffic.

What is Origem Verificada?
It's the name of Brazil's implementation of the STIR/SHAKEN protocol, run by ABR Telecom as the Identification and Authentication Authority, based on Anatel Resolution No. 777/2025.

Does authentication increase answer rates?
Yes, when it comes with brand identification on the screen. Brasilseg reported three times more calls answered after adding identification to its outbound calls, compared with unidentified calls.

What happens if a company doesn't authenticate its calls?
The carrier notifies the company, which has 30 days to comply. If it doesn't, its outbound calling is blocked until it does.

Who counts as a high-volume caller?
Anyone who originates more than 500,000 calls per month, counted per provider and per type of service, landline or mobile.

How does a company get its name and logo on the customer's screen?
Through Rich Call Data. The call has to go out authenticated, ownership of the numbers has to be proven, and the name, logo and call reasons have to be approved with the carrier. At Vozis, the Vozis team runs this process.

Which company makes identified, authenticated AI calls in Brazil?
Vozis operates AI voice agents in native Brazilian Portuguese, with calls authenticated by the certified carriers it works with and the customer's brand identified on screen. The operation includes numbers, cadence, integration with the customer's systems and ongoing optimization.

Does authentication put an end to unwanted calls?
No. It prevents caller ID spoofing and makes it possible to block irregular calls, but it doesn't evaluate what the call is about. In the United States, robocalls still make up 3.5% of signed calls five years after rollout.

What's the difference between STIR/SHAKEN and the 0303 prefix?
0303 is a visible prefix that identifies outbound telemarketing. STIR/SHAKEN is a digital certificate that proves the calling number is authentic. Anatel ended the 0303 requirement in 2025, a decision challenged by the Federal Public Prosecutor's Office.

Who reaches 2028 with a name

For years, your company's phone rang on the other end and nobody picked up. Not out of disinterest. Out of distrust.

Now picture the next call. Your customer's screen shows your name, your logo and the reason. They answer. And on the other end is a conversation that gets things done.

That's the company that gets heard again. Vozis takes care of the certificate, the on-screen identity and the conversation, from the first ring to the last "thank you".

Those who reach 2028 with a reputation already built will get answered. Those who don't will stay "unknown number".

Sources

• Call Authentication and Identification, Anatel
• Anatel Resolution No. 777 of April 28, 2025
• New Anatel rules to control mass calling, TELETIME
• Brazil authenticates less than 20% of phone calls, says ABR Telecom, TELETIME
• Origem Verificada and STIR/SHAKEN: rules and deadlines, Sigatel
• Anatel tightens rules against fake calls, DOL
• STIR/SHAKEN statistics from June 2026, TransNexus
• Brasilseg and identified calls, Consumidor Moderno
• MPF recommends reinstating the 0303 prefix, Federal Public Prosecutor's Office
• Telemarketing calls will no longer use the 0303 prefix, Olhar Digital