Activation of Voice over Internet Protocol Applications Based on Push Notifications

Systems and methods are described for communicating between VoIP applications installed on a mobile computing device and their corresponding servers using a cloud-based notification infrastructure. In one aspect, a method is performed by a notification handler executing on a mobile computing device and includes the actions of maintaining a persistent network connection between the notification handler and a notification server associated with the notification handler; receiving, over the persistent network connection, an incoming call notification for a VoIP application installed on the mobile computing device, the received incoming call notification being relayed by the notification server from a VoIP server to which the VoIP application is associated; determining, in response to the receiving of the incoming call notification, that the VoIP application is in an inactive state; and activating the VoIP application on the mobile computing device to provide information relating to the received incoming call notification.