Push Notification as an integral part of UC&C system
Push notification is a message that pops up on the screen of your mobile device when you are not using the app. In fact we’ve been using push notifications for quite a long time. An example could be a notification coming from the airlines reminding you to check in for your flight or a calendar event reminder.
Apple was the first one to introduce Push notifications in 2009, Google implemented them in 2010. Today push notifications are becoming even more powerful, and we will see why in the next chapter.
Push notification vs Polling and other techniques
In the past many VoIP apps have been using polling techniques, in which the client had to poll the server from time to time to check if there are any updates. They were not actually real-time–you received a notification not at the very time it arrived, but after the app has “polled” the server. Other VoIP apps were running in the background all the time so that the user could receive an update, over-consuming the battery.