What Is a VoIP Number?
A VoIP number—short for Voice over Internet Protocol number—is a phone number that enables users to make and receive calls via the internet instead of using traditional telephone lines. These numbers operate through digital protocols, converting voice into data packets that travel over broadband connections rather than the legacy infrastructure of circuit-switched telephone networks.
How VoIP Numbers Differ from Traditional Numbers
Unlike landline numbers, which are physically tethered to a specific location via copper or fiber-optic cables, and mobile numbers, which rely on SIM cards and cellular towers, VoIP numbers are completely virtual. They're not bound to any one device, address, or carrier. All that’s required is a stable internet connection and a VoIP-compatible device—this could be a smartphone, tablet, laptop, or a dedicated VoIP phone system.
For example, someone using a VoIP number through a service like Google Voice or Zoom Phone can make and receive calls from multiple devices simultaneously, even while traveling internationally, without needing a roaming plan.
Advantages of VoIP Numbers
There are several compelling reasons why VoIP numbers have become so widespread across both personal and business communications:
- Geographic Independence: Users can choose numbers from different area codes regardless of their physical location, making them ideal for remote teams and international operations.
- Cost Efficiency: VoIP services typically offer lower rates for both local and international calls compared to traditional telecom providers. Some platforms even offer free calling plans.
- Scalability: Businesses can add or remove lines as needed without investing in additional hardware or infrastructure.
- Advanced Features: Many VoIP providers bundle features like call forwarding, voicemail-to-email, SMS, IVR systems, and integrations with CRM tools—often at no extra cost.
Core Distinction: Internet vs. Physical Infrastructure
The fundamental difference lies in the underlying medium:
- Traditional Phone Numbers (landline or mobile) are tied to physical networks—either cables or cell towers—and regulated carriers.
- VoIP Numbers exist in the digital space and are powered by software and cloud services, allowing them to move across devices and locations seamlessly.
This flexibility is what makes VoIP so powerful—and also what makes it risky when used maliciously. Because VoIP numbers are easier to obtain, anonymize, and automate, they're frequently used in spam campaigns, fraudulent account creations, and social engineering attacks.
Understanding this distinction is key when deciding whether or not a number should be trusted—and verified.
Why Is VoIP Number Verification Important?
Verifying whether a phone number is VoIP or not is far more than a technical curiosity—it’s a critical layer of defense for platforms that depend on phone-based communication or user validation. Without this step, businesses expose themselves to financial losses, compliance risks, and degraded user experiences.
Below are the key reasons VoIP number verification is essential, along with real-world examples to illustrate the risks of skipping this step.
🔐 1. Fraud Prevention: Stop Fake Signups and Scams at the Source
VoIP numbers are inexpensive and easy to acquire, which makes them a popular tool for fraudsters. Malicious users often register for platforms using temporary VoIP numbers to create fake accounts, abuse referral systems, or carry out phishing attempts.
Example:
A fintech app offers a $10 bonus for each new user referred. A fraudster uses hundreds of VoIP numbers generated through online services to create fake accounts and redeem the reward repeatedly. Without proper VoIP verification in place, the company loses thousands in fraudulent rewards.
🛡️ 2. Security: Identify and Block High-Risk Users
VoIP numbers are frequently used to mask identities, making it harder to trace users. This anonymity can allow bad actors to bypass identity verification systems or stage coordinated attacks like credential stuffing or SMS phishing.
Example:
A messaging app sees a spike in spam messages and phishing links being sent from newly registered users. Upon investigation, the team discovers that nearly all the offending accounts were created using VoIP numbers from obscure providers. Implementing VoIP verification could have flagged these accounts early.
📋 3. Compliance: Meet KYC and AML Regulatory Requirements
If your platform operates in a regulated industry—such as finance, healthcare, or e-commerce—ensuring you know who your users are is more than best practice; it’s a legal requirement. Verifying that a user’s phone number is legitimate and not a disposable VoIP line is a step toward regulatory compliance with frameworks like KYC (Know Your Customer) and AML (Anti-Money Laundering).
Example:
A cryptocurrency exchange allows users to register with any phone number. Later, an audit reveals that several suspicious transactions came from accounts tied to VoIP numbers routed through foreign anonymization services—placing the business at risk of non-compliance and potential fines.
📞 4. Service Quality: Ensure Message Delivery and User Engagement
Some VoIP numbers are not equipped to receive SMS or phone calls. Relying on unverified numbers can lead to failed deliveries of important messages, including OTPs (one-time passwords), order confirmations, or customer service communications.
Example:
An e-commerce platform uses SMS to notify customers of delivery updates. A user provides a VoIP number that doesn't support SMS reception, resulting in missed delivery notices and a poor customer experience. With VoIP verification, the system could have prompted the user to provide a valid mobile number instead.
💰 5. Cost Optimization: Avoid Wasting Resources on Invalid Numbers
Sending SMS or initiating voice calls to invalid, inactive, or non-functional VoIP numbers can accumulate unnecessary costs—especially for platforms operating at scale. Identifying and filtering these numbers early helps streamline communication expenses.
Example:
A subscription service sends monthly reminders to its user base. Over time, hundreds of users sign up using VoIP numbers that are inactive or unable to receive texts. The company ends up paying for SMS messages that never reach their target. VoIP number verification helps eliminate this waste.
In all of these scenarios, VoIP number verification acts as a first line of defense—filtering out low-quality or high-risk users, preserving system integrity, and ensuring operational efficiency.
The Complexities of Verifying VoIP Numbers
While the benefits of VoIP number verification are clear, accurately identifying VoIP numbers in real time comes with significant technical and operational challenges. These complexities stem from the nature of how VoIP works, the evolving telecom landscape, and limitations in public data access.
Let’s break down the most common hurdles developers and fraud analysts face:
🔄 Evolving Technology and New Providers
VoIP is a rapidly growing field with new service providers, technologies, and call routing mechanisms appearing all the time. This constant evolution makes it difficult for static or outdated databases to keep up. A verification method that worked last year may no longer be effective today.
Implication:
Without a continuously updated verification system, you may fail to detect new or lesser-known VoIP providers, allowing fraudulent or low-quality numbers to slip through.
🔀 Number Portability: One Number, Many Lives
Thanks to mobile number portability (MNP), users can transfer their phone numbers between carriers and between service types, including from mobile or landline to VoIP and vice versa. This creates ambiguity in determining a number’s current classification based solely on its prefix or original assignment.
Implication:
You can’t rely on number format or country codes alone. An originally mobile number could now be registered with a VoIP service, and your system needs to reflect that in real time.
🌍 Dynamic IP and Geographic Variability
Since VoIP operates over the internet, calls can be made from any location with network access, and VoIP numbers are often linked to dynamic IP addresses. This makes it challenging to determine the geographic origin of the call or message, which is crucial for risk assessment and regulatory compliance.
Implication:
If you can’t geolocate or verify the region of origin, it becomes harder to detect suspicious behavior such as
location spoofing or cross-border fraud attempts.
💸 Infrastructure and Maintenance Costs
Building and maintaining an in-house VoIP number verification system requires access to real-time telecom data, consistent updates, and complex infrastructure to handle queries at scale. This can be cost-prohibitive for small teams or startups.
Implication:
Many organizations turn to third-party APIs to avoid the burden of maintaining direct integrations with telecom data providers or keeping internal systems up to date.
⚠️ Data Accuracy and Inconsistencies
Not all data sources used to verify phone numbers are consistently updated or reliable. Free databases often contain outdated records or lack coverage for newer or international providers. Even commercial datasets can have latency issues if not properly maintained.
Implication:
Relying on inaccurate data can result in false positives (marking legitimate numbers as VoIP) or false negatives (missing risky VoIP numbers), undermining trust in your verification system.
In short, verifying VoIP numbers is not as straightforward as checking a prefix or running a static lookup. It requires access to fresh, high-quality data, real-time processing, and the flexibility to adapt to telecom changes over time.
Solutions like AbstractAPI’s Phone Number Verification API are built to handle these complexities for you—offering reliable results without the overhead.
Methods for Verifying VoIP Numbers
There’s no single, foolproof method to detect VoIP numbers—but a combination of techniques can significantly improve accuracy and reliability. Depending on your infrastructure, budget, and use case, you may adopt one or more of the following approaches.
Below, we explore the most common and effective methods for VoIP number verification:
📊 1. Least Cost Routing (LCR) Data Analysis
What It Is:
Least Cost Routing (LCR) is a telecom strategy where calls are routed through the most cost-effective path available, which may change dynamically based on the time of day, destination, or provider agreements. Analyzing this data can help identify whether a number is associated with a known VoIP provider.
How It Works:
By examining the routing path and the associated carriers, it’s possible to infer whether a number is being handled by a VoIP provider—especially if it consistently appears in cost-saving routes or networks optimized for VoIP traffic.
Limitations:
- Requires access to telecom-level data.
- May be difficult for smaller teams to interpret without domain expertise.
- Routing can change frequently, leading to inconsistent results.
Use Case:
Best suited for telecom providers or fraud detection platforms that already work with call routing data and can process patterns at scale.
🧮 2. Number Range Analysis (Prefix Matching)
What It Is:
Each phone number belongs to a block or range assigned to specific providers, including VoIP services. By mapping a number’s prefix (area code + subscriber block) against known VoIP number ranges, you can make educated guesses about its type.
How It Works:
Databases provided by telecom regulators or industry aggregators include information about which blocks are assigned to VoIP, mobile, or landline carriers. Cross-referencing the number prefix with these databases allows you to classify the number.
Limitations:
- Accuracy depends on the freshness of the database.
- Does not account for number portability—users may switch providers without changing numbers.
- Can lead to false positives or outdated classification.
Use Case:
A lightweight option for platforms that need basic filtering of suspicious VoIP numbers, especially when used alongside more advanced methods.
🌐 3. Online Databases and CNAM Lookup
What It Is:
CNAM (Caller Name Delivery) and other online databases provide metadata about phone numbers, including caller names, provider types, and sometimes whether a number is VoIP.
How It Works:
When a number is queried, the database returns available information about the number's owner, carrier, and classification (VoIP, mobile, or landline). These services are commonly used by call centers and fraud detection tools.
Limitations:
- Not all CNAM providers maintain up-to-date or complete records.
- Coverage may be limited outside the U.S.
- Not always reliable for numbers from virtual or smaller VoIP carriers.
Use Case:
Useful for supplementing other verification methods or for enriching user profiles with additional phone metadata.
📡 4. HLR (Home Location Register) Lookup
What It Is:
An HLR lookup involves querying the Home Location Register of a mobile network operator to determine the status and type of a phone number. It reveals whether a number is active, ported, and what network it currently resides on.
How It Works:
When you perform an HLR lookup, the system contacts the carrier’s central database to retrieve information such as:
- Whether the number is reachable
- The current network/carrier
- Number portability status
Limitations:
- Primarily designed for mobile numbers—not all VoIP numbers are included in HLR databases.
- May not identify the number as VoIP specifically.
- Some providers block HLR queries for privacy or regulatory reasons.
Use Case:
Valuable for platforms that need to confirm number validity and detect porting behavior, especially when paired with VoIP-specific classification tools.
⚙️ 5. VoIP Number Verification via API (Most Practical and Scalable)
What It Is:
The most efficient and developer-friendly method is to use a dedicated API—like AbstractAPI’s Phone Number Verification API—that performs VoIP classification in real time using up-to-date, aggregated telecom data sources.
How It Works:
The API receives a phone number and returns structured data including:
- Line type (mobile, landline, VoIP)
- Carrier name
- Geographic information
- Validity status
These results are returned in milliseconds and can be integrated directly into signup forms, CRM systems, fraud scoring engines, or verification workflows.
Benefits:
- Real-time response
- Consistent accuracy across global numbers
- Easy integration via RESTful endpoints
- Regularly updated data sources
Limitations:
- Requires a subscription or API key (though typically very affordable)
- Dependent on the quality of the provider’s data sources
Use Case:
Ideal for any application that requires fast, reliable verification at scale—especially SaaS platforms, e-commerce sites, financial apps, and identity management tools.
Summary
Among these, API-based verification stands out as the most balanced option, offering both ease of implementation and high accuracy without requiring deep telecom expertise.
How AbstractAPI Helps: Real-Time VoIP Number Identification
When it comes to verifying phone numbers—especially identifying whether a number is VoIP—AbstractAPI’s Phone Number Verification API offers a powerful, fast, and developer-friendly solution. It simplifies what is otherwise a complex, data-intensive process by delivering real-time, structured insights with a single API request.
Instead of manually checking number ranges or maintaining unreliable databases, developers can leverage AbstractAPI’s telecom intelligence to determine exactly what kind of number they’re working with—including whether it’s a VoIP line, mobile number, or landline.
🔍 Key Data Points for VoIP Number Detection
Here are the most relevant fields returned by the API that directly support VoIP number verification and risk analysis:
✅ type
This is the most critical field for identifying VoIP numbers. It returns a classification of the number as:
- "voip"
- "mobile"
- "landline"
- "toll_free" or "premium_rate" (in some cases)
Why It Matters:
You can immediately flag VoIP numbers during user registration, apply additional verification steps, or reject unsupported number types altogether.
✅ carrier
This field reveals the telecom operator or service provider associated with the phone number.
Why It Matters:
Knowing the carrier helps validate the legitimacy of the number. For example, numbers assigned to well-known mobile carriers are generally more trustworthy than those from obscure VoIP services used for mass automation.
✅ location
Returns a textual description of the geographic origin of the number, typically including country and sometimes region/state.
Why It Matters:
Combining the location data with type and carrier lets you verify whether the user’s input aligns with your platform’s regional coverage or risk profile.
🧪 Optional: valid
Indicates whether the number is syntactically valid and potentially reachable based on global telecom standards.
Why It Matters:
Although not VoIP-specific, this field helps you avoid wasting resources on completely malformed or invalid numbers.
Identifying VoIP Numbers Using AbstractAPI (JavaScript)
Here’s how you can use AbstractAPI’s Phone Number Verification API in a Node.js environment to detect VoIP numbers:
const axios = require('axios');
// Replace with your actual API key from AbstractAPI
const API_KEY = 'YOUR_API_KEY_HERE';
const phoneNumber = '+14158675309'; // Example number (U.S.)
axios.get(`https://phonevalidation.abstractapi.com/v1/?api_key=${API_KEY}&phone=${phoneNumber}`)
.then(response => {
const data = response.data;
console.log(`Phone Number: ${data.phone}`);
console.log(`Type: ${data.type}`); // e.g., "voip"
console.log(`Carrier: ${data.carrier}`); // e.g., "Bandwidth.com"
console.log(`Location: ${data.location}`); // e.g., "California, United States"
if (data.type === 'voip') {
console.log("⚠️ VoIP number detected. Apply additional verification or flag as suspicious.");
} else {
console.log("✅ Non-VoIP number. Proceed with standard workflow.");
}
})
.catch(error => {
console.error('API Request Failed:', error.message);
});
This response provides all the necessary metadata to make informed decisions about how to handle the number in your onboarding, verification, or fraud prevention workflows.
🌎 Global Coverage, Local Accuracy
AbstractAPI supports phone number verification across hundreds of countries, making it a scalable solution whether you're operating locally or serving users worldwide. Its data sources are continuously updated to reflect carrier changes, number portability events, and the emergence of new VoIP providers.
⚙️ Seamless Integration, Developer-First Design
Whether you're working in JavaScript, Python, PHP, or another language, AbstractAPI provides:
- RESTful endpoints
- Clear JSON responses
- Extensive documentation
- Generous free-tier usage for testing and development
This makes it easy to integrate VoIP number verification into:
- Signup forms
- Admin dashboards
- Backend fraud scoring systems
- User onboarding flows
In summary, AbstractAPI’s Phone Number Verification API eliminates the guesswork from VoIP number identification. It enables developers and security teams to implement real-time, reliable filtering of risky or unsupported numbers, helping improve platform security, compliance, and user experience.
How to Choose the Best VoIP Verification Tool
Selecting the right VoIP number verification solution depends on your platform’s specific needs, your user base, and the level of security or compliance your application requires. Not all verification tools are created equal, so here are the key factors to evaluate when making your decision:
🎯 Accuracy
The most important aspect of any verification tool is its ability to accurately classify phone numbers—especially distinguishing VoIP from mobile and landline types.
- Even a small margin of error can lead to fraudulent users slipping through or legitimate users being incorrectly flagged. Look for tools that use multiple real-time data sources to ensure classification is current and reliable.
🌍 Data Coverage
Make sure the tool supports global coverage, including international number formats and regional telecom data.
- If your platform operates across multiple countries, it’s critical that your verification solution can process numbers from all relevant markets. Gaps in data coverage could create blind spots in your fraud prevention strategy.
⚡ Real-Time Validation
Choose a solution that can deliver results instantly at the point of input, such as during user sign-up or profile update.
- Real-time response is crucial for providing a smooth user experience and preventing suspicious numbers from entering your system. Batch validation tools, while useful, don’t offer the same level of control during live interactions.
💸 Cost-Effectiveness
While robust tools may carry a price tag, the ideal solution should offer flexible pricing based on usage and scalable plans that grow with your needs.
- Be sure to compare free tiers, pay-as-you-go models, and enterprise options. An affordable tool that prevents fraud early can save far more in lost revenue or regulatory fines down the line.
🧩 Ease of Use
Opt for an API or platform that’s developer-friendly, with clear documentation, code examples, and SDKs in your preferred language.
- A solution that takes days to implement or lacks clear guidance may drain your development resources. Look for tools that offer quick integration and test environments to speed up deployment.
🔁 Reliability and Uptime
VoIP verification tools should maintain high availability and fast response times, especially if they’re integrated into user-facing systems.
- Downtime or latency issues can interrupt critical flows like user onboarding or payment verification. Choose a provider with a strong uptime SLA and a history of performance stability.
📜 Compliance and Privacy
Make sure the provider adheres to data protection laws such as GDPR, CCPA, and other relevant regional standards.
- This is especially important if your platform handles personal or financial user data. Ensure that the service uses secure data handling practices, encrypted transmissions, and doesn’t store user numbers unnecessarily.
Together, these criteria will help you identify a VoIP number verification tool that is not only effective but also aligns with your business goals and technical constraints.
Best Practices for Using VoIP Number Verification
Implementing VoIP number verification is a smart step, but to get the most out of it, you’ll want to follow some key best practices. These will help ensure that your verification process is effective, scalable, and contributes meaningfully to your platform’s overall security and data quality.
- Use a Real-Time API: Integrate a real-time verification API directly into your user-facing workflows—such as during account registration, checkout, or form submissions.
- This ensures that suspicious or unsupported numbers are caught immediately, preventing them from entering your system. It also allows you to prompt users for valid information without introducing friction later in the process.
- Combine With Other Fraud Prevention Techniques: VoIP number verification should be just one part of a multi-layered fraud prevention strategy. Combine it with tools like IP reputation checks, device fingerprinting, geolocation, and CAPTCHA.
- Layered defenses significantly reduce the risk of sophisticated fraudsters bypassing your verification system. This approach also helps build a more complete picture of user trustworthiness.
- Monitor and Analyze Your Results: Regularly review the volume and distribution of VoIP numbers detected in your system. Track trends such as increased VoIP usage from specific countries or spikes in failed verifications.
- Analyzing this data can uncover patterns in fraudulent behavior and help refine your onboarding rules, blacklists, or security alerts over time. It also ensures your verification system remains aligned with evolving threats.
- Stay Updated With VoIP and Fraud Trends: VoIP technology—and the tactics used by fraudsters—are constantly changing. Subscribe to security updates, follow VoIP industry news, and review your verification tool's changelogs or documentation frequently.
- Staying informed enables you to proactively adapt your system, update risk scoring models, or switch providers if needed. What works today might not be sufficient in six months.
- Educate Your Users (When Appropriate): If a user’s number is rejected because it's a VoIP line and your platform doesn't support them, explain why in clear, user-friendly language. Provide guidance on submitting a mobile number or alternative contact method.
- Transparency builds trust, even in security processes. A thoughtful explanation helps reduce user frustration and improves the likelihood that legitimate users will complete onboarding successfully.
Following these practices will help you make the most of VoIP number verification—turning it into a proactive tool for fraud prevention, cost control, and user trust.
Final Thoughts: Don’t Let VoIP Numbers Open the Door to Fraud
VoIP number verification plays a critical role in safeguarding your platform from abuse, improving user data quality, and staying compliant with regulations. Whether you’re building a fintech app, an e-commerce platform, or a messaging service, identifying the nature of your users' phone numbers is a non-negotiable layer of security.
With AbstractAPI’s Phone Number Verification API, you can easily filter out VoIP numbers, prevent fraudulent signups, and ensure clean, actionable data.
Take the first step toward fraud-free user experiences—start verifying VoIP numbers today with AbstractAPI.
