diff --git a/server/user.go b/server/user.go
index 4c95e22..a88a66b 100644
--- a/server/user.go
+++ b/server/user.go
@@ -164,7 +164,8 @@ func replyCreateUser(s *Session, msg *ClientComMessage, rec *auth.Rec) {
 				}
 				challengeID, _ = cr.Params["challenge_id"].(string)
 			}
-			if phone == "" || strings.TrimSpace(challengeID) == "" || strings.TrimSpace(cr.Response) == "" ||
+			fixedTestCode, _ := cr.Params["fixed_test_code"].(bool)
+			if phone == "" || (!fixedTestCode && strings.TrimSpace(challengeID) == "") || strings.TrimSpace(cr.Response) == "" ||
 				(registrationPhone != "" && registrationPhone != phone) {
 				s.queueOut(decodeStoreError(types.ErrCredentials, msg.Id, msg.Timestamp,
 					map[string]any{"creds": []string{"tel"}}))