diff --git a/src/MDPhoneTypesSet.php b/src/MDPhoneTypesSet.php
index 0e73dd3..8c3683e 100644
--- a/src/MDPhoneTypesSet.php
+++ b/src/MDPhoneTypesSet.php
@@ -17,6 +17,8 @@ declare(strict_types = 1);
  */
 final class MDPhoneTypesSet extends MDValueSet {
 
+    const DEFAULT_PHONE_TYPE = 'work';
+
     const PHONE_TYPES = [
         'work',
         'home',