Validate US Phone Number Format in Contact Form 7

functions.php

<?php
// Validate Phone Numbers for US
function validate_phone( $phone ) {
  return preg_match( "/^\(?([0-9]{3})\)?[-.●]?([0-9]{3})[-.●]?([0-9]{4})$/i", $phone ); // @link https://www.oreilly.com/library/view/regular-expressions-cookbook/9781449327453/ch04s02.html
}

add_filter( 'wpcf7_validate_tel', 'tc_validate_tel', 20, 2 );
add_filter( 'wpcf7_validate_tel*', 'tc_validate_tel', 20, 2 );

function tc_validate_tel( $result, $tag ) {
  $type = $tag['type'];
  $name = $tag['name'];
  $value = $_POST[$name];

  if( validate_phone( $value ) ) :
    
  else :
    $result->invalidate( $tag, wpcf7_get_message( 'invalid_us_phone' ) );
  endif;

  return $result;
}

add_filter( 'wpcf7_messages', function( $messages ) {
  return array_merge( $messages, array(
    'invalid_us_phone' => array(
      'default' => __( 'Invalid US Phone format, use the XXX-XXX-XXXX format.' )
    ),
  ) );
} );