Did you know that up to 15% of your SMS campaigns are wasted being sent to inactive or invalid numbers? In this article, you’ll learn how to use HLR lookup to verify phone numbers and optimize your mobile communication strategies in 2025.

The HLR (Home Location Register) lookup allows you to get accurate information about the current status of any mobile phone number before launching your campaigns. This verification process will show you if a number is active, if it has been ported to another operator or if it simply no longer exists on the network.

In addition, HLR lookup positioning makes it easier to identify the geographical location of the device, key information to segment your campaigns by region. Remember that implementing an API to verify phone numbers using HLR lookup improves the effectiveness of your mailings by only directing them to valid numbers.

Below, we will show you step by step how the HLR system works, the available verification methods and how to implement this technology in your processes. You’ll also discover the operational advantages it offers in 2025: reduced costs, improved delivery rates, and elimination of failed shipments.

What is HLR and how is the registry structured?

The Home Location Register (HLR) functions as the main database of a mobile network, where permanent information on all registered users is stored. This component is fundamental in CDMA, TDMA and GSM networks, acting as the central repository that guarantees user connectivity.

Home Location Register (HLR) components

The HLR operates as a centralized database containing fields of critical information about each user. It stores the IMSI (International Mobile Subscriber Identity), a unique identifier for each SIM card authorized to connect to the network. This code is essential for authenticating users within the system.

The record also includes the MSISDN (Mobile Station International Subscriber Digital Number), which corresponds to the phone number used to contact a specific user. Unlike IMSI, this identifier is not permanently linked to a SIM card, but to the contracted service.

The HLR additionally stores:

• Services contracted and available to each user
• Restrictions on access to certain services
• Partial information about the current location of the device
• Registered terminal type
• User activation status on the network

For large mobile networks, there is typically one HLR for every million users. This distribution means that network elements must correctly identify which HLR contains the information of the user trying to connect.

The HLR plays a key role in facilitating services such as SMS. When you send a message, the system queries the HLR to identify the recipient’s Mobile Switching Center (MSC). If it is not available, a “message on hold” flag is set on the HLR for later delivery.

If you need to automate verification processes, you can implement an API to validate phone numbers that directly queries these databases, allowing you to check the status of multiple numbers simultaneously.

Difference Between HLR and VLR in Mobile Networks

While the HLR functions as a permanent registry, the Visitor Location Register (VLR) operates as a temporary database that stores information about users currently in a specific geographical area under the coverage of a Mobile Switching Center (MSC).

The main difference lies in their nature: the HLR contains permanent data of all users in a network, while the VLR stores dynamic and temporary information of active users in a given area.

Data

function

Management

Feature	HLR	VLR
permanence	Permanent	Temporary
Coverage	The entire network	Specific geographical area
Type of information	Static (services, identity)	Dynamics (Current Location)
Main	Subscriber	Mobility Support
Update	Rare	Constant according to movement

The VLR significantly reduces HLR queries, improving network efficiency. When a user turns on their device or moves to a new area, the corresponding VLR communicates with the HLR to verify permissions and available services.

This information is temporarily kept in the VLR while the terminal remains on, being updated periodically to prevent fraud. For example, if a prepaid user runs out of balance, this update prevents improper calls.

The VLR also plays an essential role in HLR lookup positioning, providing accurate data on the device’s current location within its coverage area. To illustrate: if the HLR functions as the official student record of a university, the VLR would be the daily attendance list of each class, constantly changing according to the presence of the students.

When you make a query using HLR lookup, the system interrogates both the HLR and the corresponding VLR to obtain complete information on the status and location of the number consulted, providing accurate data to optimize your communication campaigns.

Technical operation of the HLR Lookup step by step

How exactly does HLR lookup verification work? We explain the complete process that connects directly to mobile operators’ databases to obtain real-time information about any phone number.

IMSI query and comparison with active SIM

Step 1: The process begins when you submit a query request via the SS7 protocol (Signaling System Number 7), including the user’s MSISDN in international format. Once this request is received, the system automatically extracts the IMSI (International Mobile Subscriber Identity) associated with that number.

The IMSI works like the ID of each SIM card and is made up of three parts:

• MCC (Mobile Country Code): A three-digit code that identifies the subscriber’s country
• MNC (Mobile Network Code): A two- or three-digit code that identifies the mobile network within that country
• MSIN (Mobile Subscriber Identification Number): Unique number that identifies the subscriber within the mobile network

Step 2: During verification, the system compares the IMSI registered in the HLR database with the number assigned to the active SIM card. This comparison allows you to know if the number is currently registered and operational on the operator’s network.

Here’s a practical example. If you analyze an IMSI as a 214071234567890, you can break it down like this:

• MCC: 214 (Spain)
• MNC: 07 (Movistar)
• MSIN: 1234567890 (Unique Subscriber Identifier)

If you need to automate this verification process, you can implement a phone number verification API that directly queries these databases, allowing you to check the status of multiple numbers simultaneously.

Possible states: active, inactive, ported, call_barred

Once the HLR query is complete, you will receive information about the current status of the verified number. The main statuses you can get are:

format

State	Description	Recommended action
Active/Valid	The number is registered and operational on the network	Proceed with communication
Inactive/Absent	The number is temporarily unavailable (off or without coverage)	Retry later
Unknown	The number could not be identified or is not in the correct	Verify Number Format
Been	The user has changed operators while keeping the same number	Update Carrier Data
Call_barred	The number is blocked by the operator	Ask the user to contact their operator
Undeliverable	Verification not completed (number not assigned)	Remove from Database

Remember that when a number has been ported to another carrier, the HLR lookup provides you with both the original and current carrier. This information is especially useful for optimizing message routing and reducing costs.

In addition, you can detect if a user is roaming, valuable information for international campaigns and to evaluate the temporal geographical positioning of your contacts.

Interpretation of MCC and MNC codes

MCC and MNC codes are the keys to accurately identifying the mobile network to which a number belongs. The combination of the two (known as MCCMNC) uniquely identifies every mobile operator in the world.

The MCC (Mobile Country Code) uses three digits to identify each country:

• 214: Spain
• 310: United States
• 334: Mexico

The MNC (Mobile Network Code) identifies a specific operator within a country. In Spain, some examples are:

• 01: Vodafone
• 03: Orange
• 07: Movistar

When performing an HLR lookup, these codes allow you to determine not only if a number is active, but also to which carrier it belongs exactly. This information is crucial for optimizing message routing and reducing costs, especially when you’re working with large volumes of numbers.

The correct interpretation of these codes also facilitates the identification of ported numbers, as the system can detect discrepancies between the original operator (according to the numbering range) and the current operator (according to the MCCMNC).

Therefore, HLR lookup positioning not only verifies the validity of numbers, but also provides you with a complete x-ray of the status and location of each number within the global mobile telecommunications ecosystem.

How to check if a number is active using HLR

Verifying mobile numbers using HLR lookup allows you to confirm in real-time if a number is active before including it in your communication campaigns. This validation process improves the effectiveness of your mobile marketing strategies by removing invalid numbers.

Individual validation from dashboard

To verify an individual number, follow these simple steps on most available platforms:

Step 1: Access your dashboard in services like SMSAPI
Step 2: Go to “More Features” and select “Check Number – HLR”
Step 3: Enter the number you want to verify in international format
Step 4: Tap verify and get results in seconds

Captain Verify and LabsMobile offer similar forms where you can enter the number for immediate results. We recommend using this method when you need to confirm specific contacts before important actions.

Individual verification results include:

• Number Status (Active/Inactive)
• Current operator
• Portability information
• Roaming status
• Operator MCC/MNC codes

Bulk upload of databases for verification

If you need to validate large volumes of numbers, bulk verification using files is more efficient. This feature allows you to verify hundreds or thousands of numbers simultaneously.

Process for bulk verification:

Step 1: Prepare a CSV or Excel file with the numbers in international format
Step 2: Access the HLR verification section on your platform
Step 3: Upload the file using the appropriate option
Step 4: Start the verification process

Automatic notifications upon completion of validation

Bulk verifications can take time, which is why most services include notification systems that alert when the process is complete. These notifications eliminate the need to constantly monitor status.

HLR verification reports include additional columns with all the information obtained: number status, carrier, country, portability, and roaming. This information is essential to keep your database up to date and optimize your campaigns.

The cost varies depending on the provider and volume of verified numbers, with prices ranging from €0.006 to 0.1 credits per query, depending on the type of verification and information obtained.

Automation with APIs to validate phone numbers

If you’re going to use phone number verification services on a regular basis, we recommend automating the process using APIs. HLR lookup APIs allow you to integrate this functionality directly into your existing systems, eliminating the need for manual validations.

REST API integration into internal systems

Integrating an API to validate phone numbers into your internal systems can be completed in less than three minutes. This process allows you to programmatically query the HLR from any application, website, or management system you use.

The implementation process varies depending on the programming language you use:

curl --location --globoff 'https://dashboard.verificaremails.com/myapi/phone/validate/single?term=34677934019&auth-token={{api_token}}'

HLR lookup service providers offer two main types of APIs:

Type

results

API	Characteristics	Recommended Use
Synchronous	Process one number per request with immediate	Real-time validation, VoIP, SMS routing
Asynchronous	Processing files with results via callbacks	Bulk Processes, Database Validation

If you need to process large volumes of numbers, the asynchronous API is optimized for these cases, processing requests in parallel and returning results using HTTP callbacks.

HLR Lookup API White Paper

The white paper details the available endpoints, required parameters, and response formats to successfully implement the HLR lookup service.

The basic endpoint usually follows this structure:

https://api.dominio.com/hlr

Mandatory parameters generally include:

• api_key: Primary Authentication Credential
• api_secret: Secret code to validate the request
• requests/numbers: Array or string with the numbers to be verified in international format

Responses are returned in JSON format with structured information:

{
"id": "364637",
"term": "34677934019",
"request_id": "364637",
"result_code": "114",
"result_type": "Inconclusive",
"result": {
"id": "364215",
"term": "34677934019",
"request_id": "364215",
"result_code": "101",
"result_type": "Conectado",
"result": {
"phone_number": "+34677934019",
"number_type": "mobile",
"timezone": "Atlantic/Canary",
"format": {
"e164": "+34677934019",
"international": "+34 677 93 40 19",
"national": "677 93 40 19",
"rfc3966": "tel:+34-677-93-40-19"
},
"is_ported": true,
"reachable": "connected",
"processing_status": "completed",
"imsi": "214040000000000",
"current_network": {
"country_iso2": "ES",
"country_prefix": "34",
"country_name": "Spain",
"mccmnc": "21404",
"mcc": "214",
"mnc": "04",
"area": "ES",
"network_name": "Yoigo"
},
"original_network": {
"country_iso2": "ES",
"country_prefix": "34",
"country_name": "Spain",
"mccmnc": "21401",
"mcc": "214",
"mnc": "01",
"area": "ES",
"network_name": "Vodafone"
}
}
}
}

Remember that some platforms set a maximum of 10 requests per second. Exceeding this limit may result in temporary or permanent bans of your account.

Use cases: CRM, call centers, marketing platforms

The integration of the HLR lookup API offers significant advantages in various business scenarios:

CRM
SystemsAutomatic number verification allows you to keep databases up-to-date without manual intervention. When a customer registers their number in your CRM, the API can validate it instantly, preventing the capture of erroneous data.

Call Centers
By pre-confirming the validity of numbers, your agents can focus exclusively on achievable contacts, increasing their productivity by up to 15%.

Marketing
PlatformsAPI automation allows you to:

• Verify numbers before starting SMS campaigns
• Segment audiences by mobile operator
• Identify ported numbers to adjust strategies
• Automatically remove invalid numbers

If you need to integrate the service to verify numbers into your back-office systems such as your ERP, CRM or ESP, our development team can help you. You can also use existing integrations like Zapier to connect to thousands of apps without coding.

Finally, it is essential to implement robust security measures when integrating these APIs, especially when handling sensitive customer data. Integrations must comply with regulations such as GDPR, ensuring that all transmitted information is encrypted using SSL.

Operational benefits of the HLR Lookup in 2025

The economic impact of the HLR lookup on business communications is no longer an optional perk – it has become an operational necessity. The numbers speak for themselves, and companies that implement this technology reap measurable benefits from the first campaign.

Cost reduction in SMS campaigns

If you send regular SMS, we recommend implementing HLR checks before each major campaign. Saving up to 20% on the efficiency costs of your SMS campaigns is especially significant when you handle large volumes of communication.

The savings materialize in three main areas:

• Complete elimination of expenses on messages directed to inoperative numbers
• Budget optimization by focusing resources only on achievable contacts
• More accurate cost planning based on identified operators

For businesses with thousands of weekly shipments, preflight using a verification API.

Improved delivery and conversion rate

HLR lookup positioning eliminates one of the main problems of mobile marketing: errors in data capture. When your messages reach only active and valid numbers, the customer experience improves considerably.

The improvements are directly reflected in:

• Increased open and click-through rate on sent messages
• Measurable increase in overall campaign effectiveness
• More precise segmentation by operator for personalized messages

Mobile marketers confirm that this technology increases both the quality and effectiveness of campaigns, especially when you combine verification with data-driven targeting strategies.

Avoid sending to inactive or erroneous numbers

The data is conclusive: between 10% and 14% of mobile numbers in annual databases that remain switched off for more than 48 hours correspond to numbers that have been permanently abandoned. The HLR lookup automatically identifies these obsolete contacts, improving operational accuracy without manual intervention.

In addition, this service allows you to:

• Detect delivery issues to implement immediate fixes
• Update records without spending time on manual tasks
• Maintain clean databases through scheduled checks

Remember that the HLR lookup completely respects the privacy of the end user, since the consultation occurs exclusively between your service and the operator, without generating notifications or interruptions to the customer.

The combination of these benefits makes the HLR lookup an indispensable tool for any successful mobile communication strategy in 2025, especially when every percentage point of improvement in efficiency directly impacts your bottom line.

Recommended frequency for validating databases

When should you verify your phone numbers? The frequency of validation using HLR lookup determines the success of your mobile communication campaigns. We recommend that you establish a schedule of periodic checks to keep your databases updated and effective.

Indicators of loss of effectiveness in campaigns

Some symptoms will alert you to the need to clean your database using HLR lookup positioning. If the open rate of your marketing emails drops below 15%, providers like Gmail or Outlook will filter your messages into spam folders. A spam complaint rate of more than 0.1% in a shipment is a critical signal.

Pay attention to these key indicators:

• Progressive increase in message bounce rate
• Constant reduction in conversion rate
• Increased costs per conversion achieved
• Decrease in overall engagement in your campaigns

Good practices for regular contact cleaning

We recommend that you perform full checks on your databases at least every quarter. For specific segments like attendees at events or trade shows, check the numbers immediately before launching any targeted campaigns.

Contacts from rented, borrowed, or purchased lists should be removed from your databases or included as an exclusion list to protect your sending reputation. This practice optimizes your resources by directing efforts only towards valid contacts.

For large databases, implement a “progressive cleanup” system where different segments are checked in rotating cycles. This method ensures that your entire database is fully updated every quarter without overloading the available technical resources.

Remember that the investment in HLR verification is recouped from the first optimized campaign. The quality of your data directly determines the success of your mobile communication strategies.

HLR Legal and Compliance

When implementing HLR lookup services in your communication strategies, you should consider the legal framework that regulates these verifications. We recommend that you be aware of the specific regulations that affect the processing of contact data, as they vary depending on your jurisdiction.

Public Access to HLR Data

Did you think HLR records are publicly available? This is a common misconception. The HLR database is not publicly available and is protected by the same security systems that mobile operators use for their proprietary data. This protection is critical, as the HLR contains sensitive information, including the last known location of subscribers.

Law enforcement agencies may request data from the HLR as part of official investigations when a crime has been committed. However, commercial access to this data is strictly regulated and is done through controlled interfaces that provide only limited information necessary for specific purposes.

GDPR compliance and user privacy

The GDPR (General Data Protection Regulation) sets strict requirements for companies that process contact information. When using HLR lookup services, make sure you comply with:

1. GDPR-compliant data processing agreements with your suppliers
2. Notification of security breaches within 48 hours
3. Processing of personal data only on documented instructions from the controller

On the other hand, HLR lookup positioning plays a crucial role in SMS marketing compliance. It helps you check the status of numbers and ensure compliance with regulations that require prior consent to send promotional messages.

In addition, companies that use these services must recognize the legal implications linked to their use. Depending on your jurisdiction, you must comply with laws regarding data privacy, telecommunications, and consumer protection. It is essential to ensure that the use of HLR services complies with applicable regulations, including obtaining consent and safeguarding the confidentiality of your contacts.

Costs and scalability of the HLR Lookup service

How much should you invest in HLR verification to optimize your campaigns? The cost of HLR lookup positioning varies depending on the volume of inquiries and the provider you choose. We recommend that you evaluate these options before implementing this technology in your business processes.

Validated Number Pricing Model

HLR lookup services work on a simple and transparent pay-as-you-go system. Fees range from €0.005 to €0.010 for each verified number, with an approximate base price of €0.006 per validation. This investment is minimal compared to the savings you get by avoiding sending to invalid numbers.

If you are going to use HLR verification services on a regular basis, we recommend implementing an API to verify mobile numbers that automates the entire validation process.

Prices are structured according to the volume of enquiries:

Number of queries	Price per consultation	Price per 1000
2,500 – 5,000	€0.0059 – €0.0053	€5,85 – €5,27
10,000 – 50,000	€0.0050 – €0.0046	€5,03 – €4,56
100,000 – 500,000	€0.0043 – €0.0032	€4,33 – €3,16
1,000,000+	€0.0029 or less	€2.93 or less

The investment in HLR verification is recovered from the first campaign. Prices remain constant regardless of the country of the verified number, making it easier to plan budgets for international campaigns.

Verifying emails offers one of the most competitive costs on the market, you can see the price to verify phones with HLR in the top section of the website.

Personalized offers for high volumes

For companies that handle more than one million verifications, major providers offer special rates with additional discounts. These customized packages can reduce the cost by up to €0.0025 per consultation.

High-volume services include additional benefits:

• Automatic deduplication by storing results for 30 days
• Scheduling bulk checks at specific times
• Free trial credits (200 consultations) to evaluate the service
• Priority Technical Support

The payment options are flexible: credit card, PayPal or bank transfer, adapting to the purchasing policies of each company.

Remember that checking phone numbers is inexpensive and the effectiveness you get amply justifies the investment. Sign up for free on the available platforms and try out the service before committing to larger volumes.

Conclusion: Optimize your SMS campaigns with HLR Lookup

The HLR lookup has become a fundamental tool to optimize your mobile communication strategies in 2025. The benefits of validating phone numbers before launching your campaigns are obvious: you reduce costs, improve delivery rates, and eliminate sending to inactive numbers.

In this article, you’ve learned what HLR is and how this registry works on mobile networks. We have also analyzed step by step the technical verification process, from the IMSI query to the interpretation of MCC and MNC codes. This information allows you to make the most of the data obtained during each verification.

We recommend implementing an API to validate phone numbers to automate the verification process. This automation allows you to integrate the functionality directly into your CRM systems, call centers, or marketing platforms without manual intervention.

The operational advantages of HLR lookup positioning are clear: you can reduce costs in SMS campaigns by up to 20% by eliminating inactive numbers and significantly improve delivery rates by directing your efforts only to valid recipients.

Remember that you must validate your databases at least quarterly, paying attention to indicators of loss of effectiveness. For specific segments such as events or trade shows, verify immediately before starting the campaign.

Also, consider legal aspects and GDPR compliance. Compliance with these regulations not only avoids penalties, but strengthens your customers’ trust.

The costs of the HLR lookup service range from €0.005 to €0.010 per verified number. However, this investment is recouped from the first optimized campaign, considering the savings generated by eliminating failed shipments.

Implementing the HLR lookup is no longer optional – it’s an operational necessity for any business looking to maximize the return on their mobile marketing investments. Start integrating this technology into your current processes to position yourself favorably against the competition and improve your customer experience.

If you have any questions about implementing HLR lookup in your systems, our support team will be happy to help you optimize your mobile communication campaigns.

FAQs

Q1. What is the HLR Lookup and how does it work?
The HLR Lookup is a mobile number validation service that queries the carriers’ central database to verify if a number exists, which carrier it belongs to, and if it is active. It works by querying the HLR (Home Location Register) registry for up-to-date information on the status and location of mobile numbers.

Q2. What are the main benefits of using HLR Lookup in mobile marketing campaigns?
Key benefits include reducing costs by avoiding sending to inactive numbers, improving delivery and conversion rates by targeting only valid numbers, and optimizing contact databases. This allows for greater efficiency and effectiveness in mobile communication campaigns.

Q3. How often is it recommended to perform HLR checks on a database?
It is recommended that you perform full checks of the databases at least quarterly. For specific segments, such as event attendees, verification should be done just before starting a targeted campaign. It is important to monitor indicators of effectiveness to determine when additional cleanings are necessary.

Q4. How does the HLR Lookup integrate into a company’s existing systems?
The integration is mainly done through REST APIs that allow the verification process to be automated. These APIs can be integrated into CRM systems, call centers or marketing platforms, allowing the validation of numbers in real time or in batches, depending on the needs of the company.

Q5. What is the average cost per HLR check and how does it vary by volume?
The cost per HLR check typically ranges from €0.005 to €0.010 per number. For larger volumes, prices decrease, and can reach €0.0029 or less per query in cases of more than one million verifications. There are customized offers for high volumes that can further reduce costs. You can see the prices for HLR phone verification in the section. of the Web.