How to Stop Spam Calls and Robocalls: Complete Guide to Reporting and Protection

Spam calls aren't just annoying — they're a genuine threat. From IRS impersonation scams to fake tech support, criminals use robocalls to steal billions of dollars annually. And for businesses, spam calls waste employee time, tie up phone lines, and can even damage your reputation if scammers spoof your company's number.

The good news: you have more tools to fight back than ever before. The bad news: determined scammers will always find ways around protections. Let's break down exactly what you can do.

How to Report Spam Calls and Robocalls

Reporting spam calls helps regulators identify patterns, track down scammers, and take enforcement action. While you may not see immediate results from a single report, the aggregate data is crucial for investigations. Here's where to file complaints:

Federal Trade Commission (FTC)

The FTC is the primary agency for consumer protection against unwanted calls. They maintain the National Do Not Call Registry and pursue legal action against major violators.

• Online: reportfraud.ftc.gov
• Phone: 1-877-382-4357 (1-877-FTC-HELP)
• What to report: Unwanted sales calls, robocalls, caller ID spoofing, scam calls

Federal Communications Commission (FCC)

The FCC regulates telecommunications carriers and enforces rules about caller ID spoofing, robocalling, and carrier compliance with STIR/SHAKEN.

• Online: consumercomplaints.fcc.gov
• Phone: 1-888-225-5322 (1-888-CALL-FCC)
• What to report: Spoofed caller ID, unwanted calls to cell phones, violations by phone carriers

State Attorney General

Many states have their own telemarketing laws and enforcement mechanisms. Your state Attorney General can investigate violations of state-specific Do Not Call laws and pursue legal action against in-state scammers.

• Find yours: naag.org/find-my-ag
• What to report: Violations of state telemarketing laws, local scam operations

Your Phone Carrier

All major carriers now offer spam call reporting. This helps them improve their call-blocking algorithms and may result in blocking the number network-wide.

• AT&T: Forward spam texts to 7726 (SPAM); use AT&T Call Protect app
• Verizon: Forward texts to 7726; use Call Filter app
• T-Mobile: Forward texts to 7726; Scam Shield is automatic
• Business VoIP: Report to your provider's support team

Register for Do Not Call Lists

Do Not Call registries prohibit most legitimate telemarketers from calling registered numbers. While they don't stop illegal scammers (who ignore the law anyway), they significantly reduce calls from legitimate businesses and make it easier to identify true violations.

National Do Not Call Registry (FTC)

This is the most important registration you can make. Once registered, most telemarketers must stop calling within 31 days. Your registration never expires.

• Register online: donotcall.gov
• Register by phone: 1-888-382-1222 (call from the number you want to register)
• Verify registration: Use the same website to check if your number is registered
• Cost: Free
• Coverage: Personal landlines, personal cell phones, business lines (limited protection)

State Do Not Call Registries

Many states maintain their own Do Not Call lists with additional protections beyond the federal registry. Some states have stricter rules or additional enforcement capabilities.

State	Registry	Notes
Florida	freshfromflorida.com/donotcall	Managed by Dept. of Agriculture; strict enforcement
California	Uses federal registry only	Strong state telemarketing laws apply
Texas	texasnocall.com	Registration must be renewed every 3 years
New York	Uses federal registry only	Additional state enforcement available
Pennsylvania	attorneygeneral.gov/donotcall	Free registration; Attorney General enforcement
Indiana	indianadonotcall.org	Applies to Indiana-based telemarketers

Check with your state's Attorney General or consumer protection office to see if your state maintains a separate registry. Even if your state uses the federal list, filing complaints with state authorities can trigger additional enforcement.

Understanding STIR/SHAKEN: How Modern Caller ID Authentication Works

STIR/SHAKEN is a framework of technical standards designed to combat caller ID spoofing. The names are acronyms:

• STIR: Secure Telephone Identity Revisited
• SHAKEN: Signature-based Handling of Asserted information using toKENs

Here's how it works: when a call is placed, the originating phone carrier digitally signs the call with a certificate that verifies the calling number's legitimacy. The terminating carrier then checks this signature before delivering the call.

The Three Attestation Levels

STIR/SHAKEN assigns one of three trust levels to each call:

• Full Attestation (A): The carrier has verified the caller's identity AND that they're authorized to use the calling number. This is the highest trust level — the call is very likely legitimate.
• Partial Attestation (B): The carrier knows the customer but cannot verify they're authorized to use the specific number. Common with PBX systems where multiple numbers route through one account.
• Gateway Attestation (C): The call entered the carrier's network from an external source (international gateway, smaller carrier) and the originating caller cannot be verified. This is the lowest trust level.

How IntelliVoice Implements STIR/SHAKEN

As a telecommunications provider, IntelliVoice is fully compliant with FCC STIR/SHAKEN mandates. Here's what that means for our customers:

• Outbound calls are signed: When you make calls through our network, we digitally sign them with Full Attestation (A) when possible. This means the businesses and consumers you call see your legitimate caller ID, verified by our certificate.
• Inbound calls are verified: We check the STIR/SHAKEN signature on incoming calls and can display verification status to help you identify potentially spoofed calls.
• Caller ID reputation monitoring: We proactively monitor our number ranges to ensure they aren't flagged as spam by analytics companies like Hiya, TNS, or First Orion. If your business number gets incorrectly flagged, we have relationships to get it corrected.
• Call screening and filtering: Our auto-attendants, AI receptionists, and call routing features can screen incoming calls, blocking known spam patterns before they ever reach your employees.

Why Spam Calls Still Get Through

Despite Do Not Call registries, STIR/SHAKEN, and carrier call-blocking, you still receive spam calls. Here's why:

1. Scammers Don't Follow the Law

The Do Not Call Registry is a legal tool that only affects legitimate telemarketers who fear FTC enforcement. Criminals operating from overseas or through disposable infrastructure simply ignore it. They're already committing fraud — violating telemarketing laws is the least of their concerns.

2. STIR/SHAKEN Has Gaps

While STIR/SHAKEN has dramatically reduced domestic spoofing, it has limitations:

• International calls: Calls originating overseas often enter the US network through gateways that can't provide full attestation. Scammers exploit this by routing through international carriers.
• Smaller carriers: While major carriers are required to implement STIR/SHAKEN, some smaller providers have exemptions or incomplete implementations.
• Legitimate-looking spoofs: Scammers can still spoof numbers — they just receive lower attestation. Not all phones display attestation levels, so users may not know a call is suspicious.
• VoIP abuse: Bad actors obtain VoIP accounts with stolen identities or lax verification, then place calls that may receive higher attestation than they deserve.

3. Why the Same Scam Calls from Different Numbers

Ever notice you get the same "car warranty" or "IRS" scam call, but from a different number every time? This is called number rotation or "number churning," and it's one of the primary reasons blocking individual numbers doesn't work.

Here's how it works: Robocallers acquire massive pools of phone numbers — often thousands or tens of thousands at a time. They may purchase cheap VoIP numbers in bulk, use stolen account credentials, or exploit carriers with weak verification. A single robocall operation might place calls from 500 different numbers in a single day, using each number for just a few hours before abandoning it and moving to the next.

By the time you block a number or report it to the FTC, that number is already "burned" — the scammers have moved on and will never use it again. Your block list grows, but the calls keep coming from fresh numbers. This is why pattern-based blocking (identifying the behavior, not just the number) and carrier-level analytics are far more effective than manually blocking individual callers.

4. Neighbor Spoofing

Scammers deliberately spoof numbers with the same area code and prefix as your number — making the call appear local. People are more likely to answer calls that look like they're from neighbors, local businesses, or familiar areas.

5. Evolving Tactics

As defenses improve, scammers adapt. They now use AI-generated voices, callback scams (leaving voicemails that prompt you to call back), and hybrid approaches that start with a text message before calling.

Additional Protection Strategies

Beyond registries and carrier protections, here are additional steps to reduce unwanted calls:

For Consumers

• Use your carrier's call-blocking app: AT&T Call Protect, Verizon Call Filter, and T-Mobile Scam Shield are free and improve over time.
• Don't answer unknown numbers: Legitimate callers will leave voicemail. Scammers often won't.
• Never press buttons or say "yes": Some scam calls record your voice saying "yes" for use in fraud schemes.
• Don't call back unfamiliar numbers: Callback scams connect you to premium-rate numbers that charge your account.
• Be skeptical of urgency: "Your Social Security number has been suspended" and similar threats are always scams.

For Businesses

• Use a business phone system with spam filtering: Enterprise VoIP systems like IntelliVoice include advanced call analytics and blocking built into the platform.
• Implement call screening: Auto-attendants and AI receptionists can filter out robocalls before they reach employees. IntelliVoice offers these features as part of our Cloud PBX and contact center solutions.
• Monitor your outbound caller ID: Ensure your business numbers aren't being spoofed or flagged as spam. IntelliVoice provides Caller ID Reputation Management to protect your business identity.
• Train employees: Staff should know not to provide sensitive information to unsolicited callers, even if they seem legitimate.
• Work with a compliant provider: Your phone system provider should implement STIR/SHAKEN correctly and proactively monitor attestation levels for your outbound calls.

The Bottom Line

Stopping spam calls requires a multi-layered approach. Register for the National Do Not Call list and any applicable state registries. Report violations to the FTC and FCC. Use your carrier's spam-blocking tools. And understand that while STIR/SHAKEN has made significant progress against caller ID spoofing, it's not a complete solution.

For businesses, protecting both inbound and outbound calling reputation is essential. You need a phone system provider that implements STIR/SHAKEN correctly, monitors your number reputation, and provides tools to filter unwanted calls before they waste your team's time. IntelliVoice provides all of these capabilities — from STIR/SHAKEN compliant voice services and caller ID reputation monitoring to AI-powered call screening and auto-attendants that block spam before it reaches your team. If you're already an IntelliVoice customer, talk to your account manager about enabling these features. If you're not, schedule a demo to see how we can protect your business communications.

The fight against robocalls is ongoing. Regulators continue to pursue major violators, carriers continue to improve their detection algorithms, and new technologies emerge to verify legitimate callers. By staying informed and using available tools, you can significantly reduce the spam calls that reach you — even if you can't eliminate them entirely.

Frequently Asked Questions

How do I stop spoofed robocalls?

You can't completely stop spoofed calls, but you can significantly reduce them. Register on the National Do Not Call Registry, enable your carrier's free spam-blocking tools (AT&T Call Protect, Verizon Call Filter, T-Mobile Scam Shield), and report violations to the FTC. For businesses, use a phone system with STIR/SHAKEN authentication and caller ID reputation monitoring.

How do I block spoofed phone calls?

Start with carrier-level filtering — it's free and surprisingly good. On iPhone, toggle Settings → Phone → Silence Unknown Callers; on Android, enable Caller ID & spam protection. For heavier coverage, install Nomorobo, Hiya, or RoboKiller. For a business phone line, the most effective block is at the cloud PBX itself: enforce STIR/SHAKEN attestation levels so unverified calls never reach your auto-attendant.

How do I stop calls from spoofed numbers?

Spoofed numbers rotate constantly, so block lists fail quickly. Block the behavior, not the number: enable STIR/SHAKEN-aware filtering at your carrier or PBX, silence unknown callers on your personal phone, and route suspected spam straight to voicemail. On a business system, configure a policy that rejects calls with "C" attestation (unverified) or no attestation at all.

How do I stop someone from spoofing my caller ID?

You cannot directly stop a scammer from impersonating your number — caller ID spoofing is a network-level technique, not something the spoofed owner controls. What you can do:

• Register your numbers with the major caller ID reputation registries (TNS, First Orion, Hiya) so legitimate traffic is verified
• File complaints with your carrier and the FCC so they trace the fraudulent traffic back to the origin
• Record an outgoing voicemail clarifying you did not make the calls — reduces complaint volume while remediation is in progress
• Move to branded caller ID so your legitimate calls display a verified business name that scammers can't replicate

IntelliVoice's caller ID reputation service monitors all major registries and disputes false flags on your behalf — which is what actually resolves spoofing attacks against your numbers.

How do I report spam calls to the FTC?

Report spam calls at ReportFraud.ftc.gov or call 1-877-382-4357. You can also report to the FCC at fcc.gov/consumers/guides/stop-unwanted-robocalls-and-texts. Include the caller's number, date, time, and what was said. Reports help regulators identify and shut down major robocall operations.

What is STIR/SHAKEN and how does it stop spoofed calls?

STIR/SHAKEN is a caller ID authentication framework required by the FCC. It cryptographically verifies that the calling number hasn't been spoofed. Calls receive an attestation level: A (full verification), B (partial), or C (gateway). Carriers use this information to flag or block likely spoofed calls.

How can I prevent call spoofing on my business line?

Four-layer defense:

1. Move to a cloud PBX that signs every outbound call with full "A" STIR/SHAKEN attestation (proving you own the number)
2. Enroll your DIDs in caller ID reputation registries so analytics providers recognize your traffic as legitimate
3. Deploy branded caller ID so the recipient sees your verified business name and logo, not just a number
4. Monitor scam-trace services for unauthorized use of your numbers — and dispute within hours, not weeks

FusionUC and our Caller ID Reputation service do all four automatically, so your team doesn't have to.

How do I mitigate spoofed robocalls targeting my business?

Attacks aimed at your business (rather than using your number) call for different tactics: STIR/SHAKEN-aware SIP trunking that rejects low-attestation inbound calls at the edge, an AI-powered auto-attendant that challenges suspicious callers before they reach your team, and an incident playbook so staff know how to respond when spoofing attempts land. The goal is to make your business a low-yield, high-friction target — scammers move on fast.

Why do I still get spam calls after registering on the Do Not Call list?

The Do Not Call Registry only applies to legitimate telemarketers. Scammers and illegal robocallers ignore it entirely since they're already breaking the law. The registry is still worth joining because it stops legal telemarketing calls and gives you grounds to report violations.

How do I report a number that keeps calling me?

Forward unwanted text messages to 7726 (SPAM) — your carrier investigates. For calls, file complaints with the FTC at ReportFraud.ftc.gov, the FCC at consumercomplaints.fcc.gov, and your state attorney general. Include date, time, number, and what was said. Most carriers also have in-app reporting (AT&T ActiveArmor, Verizon Call Filter, T-Mobile Scam Shield).

How can businesses protect their phone numbers from being flagged as spam?

Use a phone system with STIR/SHAKEN attestation, register your numbers with major carriers and analytics providers, monitor your caller ID reputation, and follow responsible calling practices. IntelliVoice provides caller ID reputation monitoring and branded caller ID services to ensure your business calls get answered.