Zoe Helper: A Sigfox SOS Device - Part 2

Zoe Helper: A Sigfox SOS Device - Part 2

In this part of the project, I process the message sent by Sigfox Backend via callback. To recap, this is the message:

http://jacksonng.org/sigfox/newnotifications.php?message={data}&deviceid={device}

The job of newnotifications.php is to read the message, check who it is intended for, and send the message to the receiver's mobile device. 

Whose message is this?