Learn About Blocking Spam Calls on Your Phone

Understanding Spam Calls and How They Work

Spam calls have become one of the most frustrating problems for phone users. According to the Federal Communications Commission (FCC), Americans received approximately 3.8 billion robocalls in 2023 alone. These unwanted calls range from automated messages about fake warranties to scams targeting personal information and money.

Spam callers use various tactics to reach people. Some use software that randomly generates phone numbers, while others purchase lists of phone numbers from data brokers. Many spam operations spoof caller ID information, making their calls appear to come from legitimate businesses, government agencies, or local numbers to increase the chances that people will answer.

The types of spam calls vary widely. Robocalls deliver pre-recorded messages about supposed vehicle warranties, prescription drug discounts, or credit card offers. Scam calls attempt to trick people into revealing personal information like Social Security numbers or bank account details. Some callers claim to represent the IRS, utility companies, or tech support services. Others simply play silence or brief sounds before disconnecting.

Understanding how spam calls operate helps you recognize them when they arrive. Legitimate businesses typically call only if you've given them your number or requested their service. Unexpected calls from unfamiliar numbers, especially those offering deals or demanding immediate action, warrant skepticism. Calls asking for personal information or payment through gift cards or wire transfers are almost always scams.

Takeaway: Learn to identify spam calls by recognizing common characteristics like unexpected offers, requests for personal information, pressure tactics, and spoofed caller IDs that appear to come from familiar numbers.

Built-In Phone Features for Blocking and Filtering Calls

Modern smartphones include native tools designed to reduce unwanted calls. Both Apple and Android devices offer call-blocking and filtering features that work without requiring additional apps.

iPhone users can access call filtering through Settings. The Phone app includes a "Silence Unknown Callers" feature that sends calls from numbers not in your contacts directly to voicemail. This feature works by checking incoming numbers against your contacts, recent calls, and Siri suggestions. If a caller is not recognized, the call is silenced but still recorded as a missed call that you can review later. To enable this feature, open Settings, tap Phone, select Silence Unknown Callers, and toggle it on.

Android devices offer similar functionality through the Phone app's settings. The call screening feature, available on newer Google Pixel phones and some other Android devices, can automatically answer suspected spam calls and transcribe them. Users can screen calls directly by tapping the "Screen call" button to have Google Assistant answer and ask the caller's purpose. Android users can also set specific contacts to go directly to voicemail or block numbers individually.

Both platforms allow you to block specific numbers manually. On iPhone, you can block a contact by opening their contact card and selecting "Block this Caller." On Android, open the Phone app, find the unwanted number in your call history, tap the three-dot menu, and select "Block number." Blocked callers can still leave voicemails, though they typically won't be notified that they've reached voicemail.

For additional filtering on iPhone, you can enable "Filter Unknown Senders" in the Messages app, which separates messages from unknown contacts into a separate tab. Some carriers also offer free call-filtering services through their networks. AT&T offers Call Protect, Verizon offers Call Filter, and T-Mobile offers Scam Shield—these services screen calls before they reach your phone.

Takeaway: Activate your phone's native call-blocking features by adjusting settings for unknown callers and manually blocking specific numbers. These tools work without additional apps and are available on all modern smartphones.

Third-Party Apps and Services for Spam Call Prevention

Beyond built-in features, numerous apps specialize in identifying and blocking spam calls. Popular options include Nomorobo, RoboKiller, Truecaller, and Call Control. These apps use different approaches to protect users from unwanted calls.

Nomorobo operates by maintaining a database of known spam numbers. The app compares incoming calls against this database and blocks calls identified as spam. Nomorobo also allows users to report spam calls, which helps update the database for other users. The service is available as a free version with basic blocking, or a paid version with additional features. Nomorobo reports that its users have avoided over 2.5 billion spam calls since the service launched.

RoboKiller uses artificial intelligence to identify spam patterns. The app learns from millions of spam calls and can detect new spam calls based on characteristics like calling patterns, caller behavior, and voice patterns. RoboKiller also offers a "AnswerOnce" feature that answers suspected spam calls with a pre-recorded message, which discourages spammers from making further calls to that number. The app requires a paid subscription but offers a free trial period.

Truecaller identifies callers by cross-referencing incoming numbers against a global database of phone numbers. The app shows you the caller's identity and allows you to block spammers. Truecaller's database includes billions of phone numbers and is built through user reports and public information.

When selecting a third-party app, consider what information the app requires. Most apps need permission to access your phone's call logs and contact list. Review the app's privacy policy to understand how your data will be stored and used. Free versions of these apps typically show ads or offer limited features, while paid versions provide more comprehensive blocking and additional tools.

Takeaway: Research third-party apps that match your needs, comparing features like AI-based detection, community reporting, and pricing models. Test free versions before committing to a paid subscription.

Carrier-Level Services and Do Not Call Registration

Phone carriers provide network-level spam filtering as part of their services. These carrier tools work at the network level before calls reach your phone, making them effective against a wide range of spam.

AT&T Call Protect screens calls for spam and scam indicators. The basic version is free and includes call labeling that identifies likely spam calls. The premium version adds advanced call blocking and fraud notifications. Verizon Call Filter works similarly, identifying spam calls and allowing users to block and report spam numbers. Verizon's premium tier includes advanced blocking features. T-Mobile Scam Shield filters spam at the network level and blocks calls identified as high-risk scams. All three major carriers offer variations of these services at little or no cost to customers.

Smaller carriers and MVNOs (mobile virtual network operators) often partner with third-party spam-filtering companies to offer similar services. Check with your carrier to learn what free services are already included in your plan.

The National Do Not Call Registry offers another layer of protection, though with limitations. Registered by the Federal Trade Commission and the FCC, this registry allows consumers to list their phone numbers to opt out of telemarketing calls. To register, visit donotcall.gov or call 1-888-382-1222 from the phone you want to register. Registration is free and permanent—your number never expires on the list.

The Do Not Call Registry covers most telemarketing calls but has important exceptions. Political organizations, charities, surveys, and companies with whom you've done business in the past 18 months are not required to honor the registry. Additionally, the registry does not stop scam calls, since scammers ignore the registry entirely. However, it does reduce calls from legitimate businesses that make telemarketing calls.

To report numbers that ignore the Do Not Call Registry, file a complaint at donotcall.gov. The FTC uses these reports to identify patterns and pursue enforcement actions against violators.

Takeaway: Register with the National Do Not Call Registry at no cost, and enable your carrier's spam-filtering service, which is often free and works in combination with your phone's built-in tools.

Practical Steps to Protect Your Information and Avoid Scams

Even with blocking tools in place, some spam and scam calls will get through. Protecting yourself requires awareness and following established safety practices.

Never provide personal information to unknown callers. Legitimate businesses will not call asking for your Social Security number, bank account details, or credit card information. If a caller claims to represent your bank, the IRS, or another organization, ask them to provide a callback number and verify it independently by looking up the organization's official phone number online. The IRS, for example, never