Number Lookup API Overview

The Number Lookup API is designed to provide in-depth information about phone numbers, helping enterprises enhance their communication strategies and prevent fraud. By identifying the type of phone line (for example, mobile, landline, VoIP) and the associated carrier, the API allows businesses to optimize routing, reduce unnecessary costs, and improve customer engagement.

We leverage the same high-quality data that supports our global Super Network, ensuring superior data quality and real-time updates. Our solution is built on trusted, compliant, and authorized data sources, distinguishing us from providers who may lack the right to use such data.

What is Number Lookup?

The Number Lookup API provides real-time, accurate phone number intelligence to empower businesses to:

• Enhance communication workflows: Ensure messages and calls are effectively routed.
• Prevent fraud: Identify risks like SIM swaps, VoIP usage, and line type mismatches.
• Reduce operational costs: Use port-corrected carrier data to optimize routing and efficiency.

Built for seamless integration, the API is designed to scale with your needs, delivering high performance and reliability.

Why Choose Number Lookup?

• Accurate Intelligence: Access real-time, port-corrected, and carrier-specific data.
• Fraud Prevention: Detect risky numbers, SIM swaps, and VoIP activity to mitigate threats.
• Cost Optimization: Reduce expenses with better routing and line-type-specific insights.
• Developer-Ready: Comprehensive documentation and tools for smooth implementation.

Features and capabilities

The following sections detail the available features that make up the API.

Line type identification

Line type identification offers real time, port-corrected carrier name and phone type. The detailed line type information allows enable businesses to identify whether a phone number is mobile, landline, VoIP, or others. This insight allows enterprise to tailor their communication methods effectively, optimize the cost and avoid wasted communication attempts, and improve customer engagement.

Port-corrected data is the information of a phone number that reflects the latest carrier assignment after a number has been ported. Porting is the process of transferring a phone number from one telecom provider to another while keeping the same number. This process allows customers to switch providers without losing their existing number.

Non-port-corrected data is provided for countries outside the US and Canada, reflecting the original range holder or the carrier that first assigned the number. The Number Lookup API offers non-port-corrected data, delivering value through cost savings, improved performance, and workflow optimization based on line type.

SIM swap

A SIM swap is a type of fraud where someone tricks your mobile carrier into transferring your phone number to a new SIM card that they control. The API improves trust and security by detecting SIM card swaps, preventing phone number takeovers. It provides a date-stamp of the last SIM card issuance, acting as a crucial factor in securing digital transactions and preventing fraud such as 2FA bypass and unauthorized account access.

Advanced VoIP detection (Alpha)

Virtual phone numbers (VoIP) offer flexibility and convenience for legitimate users, but they are also increasingly exploited by bad actors to mask their identities, create fake accounts, bypass security checks, and abuse promotional offers. This abuse can lead to significant financial losses and operational challenges for businesses. To address this problem, Number lookup introduces an advanced VoIP detection feature, leveraging the power of Large Language Models (LLMs) to provide a more nuanced understanding of a phone number. The AI analyzes different aspects of a carrier in a prompt and categorize the likelihood of a carrier is associated with a VoIP provider. Each carrier is classified into one of four categories, giving a clear signal about the likelihood that numbers issued by that carrier are VoIP:

• High: The carrier is strongly associated with VoIP services. We recommend blocking, throttling, or applying additional security layer layers for these numbers.
• Likely: The carrier shows indicators suggesting a likely VoIP provider. Increased scrutiny or alternative verification methods for numbers linked to this carrier.
• Low: The carrier is consistent with traditional mobile service providers, indicating lower risk.
• No Data: Insufficient information is available to make a reliable assessment.

This classification allows enterprises to make proactive, risk-based decisions during onboarding, authentication, and engagement workflows, enhancing fraud prevention while preserving user experience.

The Reassigned Numbers Database (RND)

The Reassigned Numbers Database (RND) is a U.S. federal registry designed to help enterprises determine if a phone number has been reassigned to a new owner after being disconnected. By checking this database before sending messages or making calls, enterprises can avoid the risk of contacting the wrong person, stay compliant with the Telephone Consumer Protection Act (TCPA), and benefit from a safe harbour. This feature will be available only for U.S. numbers.

Fake account prevention

The Fake Account Prevention feature is designed to protect your applications from fraudulent activities linked to phone numbers. It includes key attributes like VoIP detection, which flags numbers from virtual operators often used in scams, and historical metadata that provides insights into a number's reliability based on its past usage. These capabilities allow you to block fake accounts proactively, ensuring that only genuine users can access your services, enhancing both security and user experience.

Requirements

The following sections outline the requirements for the various features of the Number Lookup API.

Line type use cases

Before using the Number Lookup API, we require you to declare your use cases to ensure compliance with legal and regulatory requirements and align with the rights of use of the services. Declaring use cases ensures that the data is handled responsibly, within the agreed terms, and for approved purposes such as fraud prevention, identity verification, or telecommunications optimization. More Terms and Conditions can be reviewed on this page.

Third-party license

Canada number lookup

A CLNPC license is required for Canada lookup. Please follow the below process:

1. Complete/sign Schedule B and send to ca.programs@sinch.com.
2. Complete and submit the Application Form on CLNPC directly online.
3. On receipt, CLNPC Management will assess your request and may contact you for further information. This process generally takes 10-12 business days.
4. At the close of the review period, and provided there are no unresolved questions or objections about the application, the CLNPC will provide a standard form of agreement for your review and signature.
5. Access will be authorized upon receipt of your signed agreement and payment of the admin fees. This fee is mandatory. The fee is approximately CAD2500 per year.

Please reach out to support if you have any questions regarding the process or application.

SIM swap

For SIM swap access, carrier registration and approval are required. We will guide you through the process. Please contact us to get started.

Regions