diff --git a/core/modules/telephone/tests/src/Functional/TelephoneFieldTest.php b/core/modules/telephone/tests/src/Functional/TelephoneFieldTest.php
index 16573fffa8de29320858d958294472466fe06239..001d004a4b8f3cea76ed0faba3b046f85b825cbf 100644
--- a/core/modules/telephone/tests/src/Functional/TelephoneFieldTest.php
+++ b/core/modules/telephone/tests/src/Functional/TelephoneFieldTest.php
@@ -13,7 +13,6 @@
  * Tests the creation of telephone fields.
  *
  * @group telephone
- * @group #slow
  */
 class TelephoneFieldTest extends BrowserTestBase {
 
@@ -101,26 +100,9 @@ public function testTelephoneWidget(): void {
    * Tests the telephone formatter.
    *
    * @covers \Drupal\telephone\Plugin\Field\FieldFormatter\TelephoneLinkFormatter::viewElements
-   *
-   * @dataProvider providerPhoneNumbers
-   */
-  public function testTelephoneFormatter($input, $expected): void {
-    // Test basic entry of telephone field.
-    $edit = [
-      'title[0][value]' => $this->randomMachineName(),
-      'field_telephone[0][value]' => $input,
-    ];
-
-    $this->drupalGet('node/add/article');
-    $this->submitForm($edit, 'Save');
-    $this->assertSession()->responseContains('<a href="tel:' . $expected . '">');
-  }
-
-  /**
-   * Provides the phone numbers to check and expected results.
    */
-  public static function providerPhoneNumbers() {
-    return [
+  public function testTelephoneFormatter(): void {
+    $phone_numbers = [
       'standard phone number' => ['123456789', '123456789'],
       'whitespace is removed' => ['1234 56789', '123456789'],
       'parse_url(0) return FALSE workaround' => ['0', '0-'],
@@ -133,6 +115,18 @@ public static function providerPhoneNumbers() {
       'php bug 70588 workaround - invalid port number - upper edge check' => ['99999', '9-9999'],
       'lowest number not affected by php bug 70588' => ['100000', '100000'],
     ];
+    foreach ($phone_numbers as $data) {
+      [$input, $expected] = $data;
+      // Test basic entry of telephone field.
+      $edit = [
+        'title[0][value]' => $this->randomMachineName(),
+        'field_telephone[0][value]' => $input,
+      ];
+
+      $this->drupalGet('node/add/article');
+      $this->submitForm($edit, 'Save');
+      $this->assertSession()->responseContains('<a href="tel:' . $expected . '">');
+    }
   }
 
 }