Applications can be notified about events that occur on other telephony
devices. In order to be notified of events from other devices, an application
must first subscribe to a device that is offering the specific events.
Once an application successfully subscribes to a device event, the application
can then receive events from the device.
There is a single telephony media engine event that is sent back to an
application when device events are received by the media engine. For further
information, see the following: