Push Status Indication
======================

Since version 3.34, SIPIS includes ``X-Sipis-Push-Status`` header
in its provisional responses to incoming INVITE requests.
Whenever the push status changes SIPIS will generate another
provisional response with the appropriate value of the
``X-Sipis-Push-Status`` header.

The possible values of the header are:

*  ``Alerting-Device``
*  ``Push-Notification-Sent``
*  ``Device-Making-Progress``

Alerting-Device
---------------

The ``Alerting-Device`` status means that SIPIS is trying to
alert the user's device(s) about the incoming call via push
notification service and so far no device has attempted to
answer the call.

Push-Notification-Sent
----------------------

The ``Push-Notification-Sent`` status means that SIPIS
received positive confirmation that its push notification
was accepted by a platform specific service.

Device-Making-Progress
----------------------

The ``Device-Making-Progress`` status means that SIPIS has
detected that a device is actually attempting to answer the
incoming call.