Mobile operating systems such as Android and iOS tend to put apps to sleep in order to preserve battery power. Enswitch can send push notifications to supported apps which are registered as telephone lines. At the moment only Android and Firebase Cloud Messaging (FCM) is supported.

Android/Firebase Cloud Messaging

Android apps must be released with a google-services.json file specifically for use with Enswitch. Please contact your Enswitch vendor to get this file, which you can then give to your developers.

Apps with push notification enabled will register with FCM, and will receive a unique identifier called a pn-prid in response. The app will then pass that pn-prid to Enswitch in the Contact header of the SIP registration. Whenever the app is about to receive a phone call, Enswitch will contact FCM with the pn-prid, and FCM will then tell Android to wake up the app if it has been put to sleep. Enswitch checks for a pn-prid in the registration details of telephones, so make sure your app uses a long registration time to make sure that the registration and pn-prid are not expired from Enswitch.

For your convenience, note that push notifications were tested on Android 12, with a custom build of Linphone and the required google-services.json, push notifications enabled, and a registration timeout of 86400 seconds.