fix #840 (#880)

lib/tasks/rest_dial.js

@@ -39,9 +39,9 @@ class TaskRestDial extends Task {
 
     if (this.data.amd) {
       this.startAmd = cs.startAmd;
-      this.stopAmd = cs.stopAmd;
       this.on('amd', this._onAmdEvent.bind(this, cs));
     }
+    this.stopAmd = cs.stopAmd;
 
     this._setCallTimer();
     await this.awaitTaskDone();