Using widget in ZOHO Developer console

Using widget in ZOHO Developer console

Hi there,

I am using connected apps in ZOHO Developer console. I tried configuring a telephony widget. But when I test it in sandbox version it shows this error in browser console 

Ignoring Message from: https://plugin_zohoexotelapp.zohosandbox.com with Data:[object Object] 

Can you please provide with documentation to use this widget. I have already refered  https://www.zoho.com/developer/help/extensions/embedded-apps/. 

Thank you.