Welcome to the RingCentral Community

Thank you very much, two more clarification. In the response the 'from' should be an object mentioned in documentation like,
"from": {
  "phoneNumber": "+PHONE_NUMBER",
  "name": "LOCATION_NAME",
  "location": "LOCATION_NAME"
}
And
For Inbound response :id related to local IP address mixed variable but for Outbound :id it works fine.
This also the same development issue?

After you finish development, you can apply your RingCentral client id into production, so you can login with RingCentral production account. Now you can use you sandbox account to call real phone or receive call.

Hi, Sharmilan You should use 'from'. It seems a bug for undefined with fromNumber. I will check it. For call in same company account extensions, RingCentral will show extension number for callee by default. You can try to call the widget with your own phone. Or you can set RingCentral to show phone number when call between same company account in RingCentral sandbox service web  service.devtest.ringcentral.com