Sometime Apple Push Notification doesn’t work and client reports we are not getting notification got upset.
This could be happened due to
1) Wrong certificates and PEM file
2) Invalid APN token on server database.
We can check invalid token using Apple feedback service. The feedback service (feedback.sandbox.push.apple.com on port 2196) give you information about failed push notifications. When a push notification cannot be delivered because the intended app does not exist on the device. By using this information we can remove invalid device token from database and stop sending push notifications to these device. This reduce unnecessary message overhead and improve overall system performance. Query the feedback service daily to get the list of device tokens and remove from database. Each time you connect to the feedback service, the information it returns lists only the failures that have happened since you last connected.
Please ask you server team to develop Feedback service.
waseemahmadblog 