Validating phone numbers in PHP is a key step for maintaining data integrity and reliable user contact. We'll cover four ways to implement this validation with code, discuss the pitfalls of traditional methods, and demonstrate how Abstract API provides a more dependable solution.
How to Implement Phone Number Validation in PHP
Here are three common ways to validate phone numbers in PHP. Each method offers a different approach to check if a phone number format is correct before you process it.
Dedicated Regular Expression With preg_match
This approach uses a single pattern that enforces the E.164 standard, a format of "+CCNN..." up to 15 digits. The "preg_match" function checks the phone number against this pattern. This method gives you full control over the validation pattern and adds zero external dependencies to your project, as detailed in the Symfony documentation.
function isValidE164(string $n): bool {
return (bool)preg_match('/^\+?[1-9]\d{1,14}$/', $n);
}
filter_var With FILTER_VALIDATE_REGEXP
This technique hands the heavy work of input filtration to the core PHP extension. You can still supply the same regular expression pattern for validation. Because "filter_var" works with "filter_input()", you can wire it directly into input-filter chains for POST, GET, or CLI data without extra wrapper code.
$ok = filter_var(
$n,
FILTER_VALIDATE_REGEXP,
['options' => ['regexp' => '/^\+?[1-9]\d{1,14}$/']]
);
Google libphonenumber Ports
These libraries, such as giggsey/libphonenumber-for-php or brick/phonenumber, incorporate the full metadata set that Google maintains. This means that length checks, country-specific rules, and formatting logic come built-in. You can install them with Composer via the command "composer require giggsey/libphonenumber-for-php".
// Using giggsey/libphonenumber-for-php
$util = \libphonenumber\PhoneNumberUtil::getInstance();
$proto = $util->parse($n, $iso2); // e.g. “US”
$ok = $util->isValidNumber($proto);
// Or using Brick
$p = \Brick\PhoneNumber\PhoneNumber::parse($n, $iso2);
$ok = $p->isValidNumber();
Challenges of Phone Number Validation
While these methods provide basic checks, they come with significant drawbacks that can compromise data quality and create maintenance overhead for your PHP application.
- International number plans evolve constantly. A static regex in preg_match or filter_var misses cases, and even libphonenumber needs frequent metadata updates to stay accurate and avoid validation errors.
- A number can pass E.164 syntax checks with preg_match yet be unreachable due to number portability or VoIP systems. This structural validation alone does not confirm a number is active or in use.
- Phone data decays quickly, so metadata cached in a library like libphonenumber becomes outdated. This requires constant package rebuilds and production rollouts to keep data fresh, which complicates development cycles.
- Mature libraries like libphonenumber still struggle with edge cases. Problems with maximum length, local-only numbers, or shared country codes force developers to patch rules or add custom logic on top of the library.
Validate Phone Numbers with Abstract API
Ensure accurate user data and improve communication by validating phone numbers in your PHP project.
Get started for free
How Abstract API Handles Phone Number Validation in PHP
Abstract API addresses the core weaknesses of traditional methods because it connects each request to a continuously updated telecom data graph.
- It replaces brittle pattern checks with authoritative telecom facts. A single call returns validity, location, carrier, and line type, which closes common fraud vectors.
- The API removes the need for home-grown lookup tables that go stale. It maintains current data on more than 190 country numbering plans, new ranges, and carrier information.
- It bypasses slow SMS round-trip checks that often fail to detect landlines and virtual numbers. The API returns the line type in real time, so you can gate features like SMS two-factor authentication for mobile lines only.
How to Add Abstract API to Your Dev Environment
Once you understand Abstract’s capabilities, to add its phone number validation API to your project is simple.
- Sign in at Abstract API, create a Phone Validation API project, and copy your key.
- In your project root, run the command: composer require abstractapi/php-phone-validation.
- Require Composer’s autoloader if your project does not already: require 'vendor/autoload.php';.
- Configure the SDK once at boot with your API key.
- Call the API wherever you collect phone input.
- Act on the enriched response, for example, reject a number if it is not valid.
<?php
use Abstractapi\PhoneValidation\AbstractPhoneValidation;
AbstractPhoneValidation::configure('YOUR_API_KEY');
$info = Abstractapi\PhoneValidation\AbstractPhoneValidation::verify('+14152007986');
if (!$info->valid) {
throw new \RuntimeException('Invalid phone');
}
echo $info->format->international;
echo $info->carrier;
echo $info->line_type;
?>
Sample Phone Number Validation Implementation
The PHP code sends a request to the API with the phone number "+14152007986". In return, the API provides a detailed JSON object. This response confirms if the number is "true" for valid, its line type, carrier, and location. You can use this data to confirm the number exists and belongs to a mobile line in the expected country.
The sample output below shows a valid US mobile number. The API returns that the number is valid, its country code is "US", its type is "mobile", and its carrier is "T-Mobile USA, Inc.". The format object also provides both international and local display versions for your user interface.
{
"phone": "14152007986",
"valid": true,
"format": {
"international": "+14152007986",
"local": "(415) 200-7986"
},
"country": {
"code": "US",
"name": "United States",
"prefix": "+1"
},
"location": "California",
"type": "mobile",
"carrier": "T-Mobile USA, Inc."
}
Final Thoughts
Traditional validation methods often fail because they only check format, not real-world status, and rely on data that quickly becomes stale. Abstract API overcomes these issues with a direct connection to live telecom data for an accurate, real-time view of any phone number. To reliably validate user phone numbers, create an account on Abstract API and get your free API key.
Validate Phone Numbers with Abstract API
Validate phone numbers in your PHP application to maintain clean data and prevent fake users.
Get started for free
