diff --git a/src/main/java/com/kimgo/wepush/controller/CallerController.java b/src/main/java/com/kimgo/wepush/controller/CallerController.java
index e031cef..1e01384 100644
--- a/src/main/java/com/kimgo/wepush/controller/CallerController.java
+++ b/src/main/java/com/kimgo/wepush/controller/CallerController.java
@@ -23,6 +23,10 @@ public class CallerController {
         if(accessToken == null){
             return ServerResponseEntity.fail("accessToken cannot be empty.");
         }
+        if(callInfo.getPhoneNumber().equals("null") || callInfo.getCallTime().equals("null")){
+            logger.info("CallInfo has null String.");
+            return ServerResponseEntity.fail("json body value error.");
+        }
         return callService.getPhoneNumber(accessToken,callInfo);
     }
 }