The operating status of the second mobile phone is then displayed on the first mobile phone as part of the contact information of the "remote user", giving the user a quick status update on whether or not that particular iPhone user is available.
The system would call upon several modules of both the device hardware and the operating system, as highlighted in the diagram filed in the patent above, such as the "operating mode" of the device (411), the user's time zone (412), the current GPS location (413), the received signal strength indicator (414), the condition of the device's Wi-Fi (415) and the battery charge level (416).
This information would then be fed into a new "status sharing module", which would sit alongside the contacts module on both users' devices and the data would be transmitted across the network (the patent filing lists a cellular network, although it is presumed the new feature would also work over Wi-Fi as well) to a central registration module and phone status database. As in the case of iMessage, the new service would presumably be tied to the user's Apple ID or phone number in order to manage the statuses.
Although the patent application was filed back in February of last year, it has not yet been officially granted by the United States Patent and Trademark Office (USPTO). Apple notes that the feature would be useful to consumers because "incoming voice calls to mobile devices can be intrusive under certain situations" and it is "desirable to allow callees to screen calls and decide in advance whether the calls warrant answering."