iPhone wallet not giving back device ID and Push token

Question

I ran into a problem while integration "Registering a Device to Receive Push Notifications for a Pass" web service on my server for Apple Passes. Link Below: https://developer.apple.com/library/content/documentation/PassKit/Reference/PassKit_WebService/WebService.html.

I've followed the following steps:

1. Able to successfully generate and distribute Apple Pass on iPhones through a downloadable link.

2. Once pass is downloaded, I'm adding that pass to Apple Wallet. While adding, Registration web service is called which must send my server a Device ID and Push Token, but I am getting these two parameters as nil.

3. However when I'm hitting the same URL on AdvanceRestClient(with dummy Device ID and Token), I do get the callback.

I wanted to know why I'm not getting device Id and Push token from iPhone??