diff --git a/core/attributedef/AttributePhoneNumber.php b/core/attributedef/AttributePhoneNumber.php
new file mode 100644
index 000000000..963e74217
--- /dev/null
+++ b/core/attributedef/AttributePhoneNumber.php
@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * Specialization of a string: phone number
+ *
+ * @package     iTopORM
+ */
+class AttributePhoneNumber extends AttributeString
+{
+    /**
+     * Useless constructor, but if not present PHP 7.4.0/7.4.1 is crashing :( (N°2329)
+     *
+     * @see https://www.php.net/manual/fr/language.oop5.decon.php states that child constructor can be ommited
+     * @see https://bugs.php.net/bug.php?id=79010 bug solved in PHP 7.4.9
+     *
+     * @param string $sCode
+     * @param array $aParams
+     *
+     * @throws \Exception
+     * @noinspection SenselessProxyMethodInspection
+     */
+    public function __construct($sCode, $aParams)
+    {
+        parent::__construct($sCode, $aParams);
+    }
+
+    public function GetValidationPattern()
+    {
+        return $this->GetOptional('validation_pattern',
+            '^' . utils::GetConfig()->Get('phone_number_validation_pattern') . '$');
+    }
+
+    public static function GetFormFieldClass()
+    {
+        return '\\Combodo\\iTop\\Form\\Field\\PhoneField';
+    }
+
+    public function GetAsHTML($sValue, $oHostObject = null, $bLocalize = true)
+    {
+        if (empty($sValue)) {
+            return '';
+        }
+
+        $sUrlDecorationClass = utils::GetConfig()->Get('phone_number_decoration_class');
+        $sUrlPattern = utils::GetConfig()->Get('phone_number_url_pattern');
+        $sUrl = sprintf($sUrlPattern, $sValue);
+
+        return '<a class="tel" href="' . $sUrl . '"><span class="text_decoration ' . $sUrlDecorationClass . '"></span>' . parent::GetAsHTML($sValue) . '</a>';
+    }
+
+}
\ No newline at end of file