diff --git a/lib/resources/numbers.js b/lib/resources/numbers.js
index b275123..c245009 100644
--- a/lib/resources/numbers.js
+++ b/lib/resources/numbers.js
@@ -80,10 +80,10 @@ export class PhoneNumber extends PlivoResource {
      * @promise {@link PlivoGenericResponse} return PlivoGenericResponse Object if success
      * @fail {Error} return Error
      */
-    buy(appId) {
+    buy(number,appId) {
         return new PhoneNumberInterface(this[clientKey], {
             id: this.id
-        }).buy(appId);
+        }).buy(number,appId);
     }
 }