This article provides additional information about the Sophos Mobile Security SMS spam filtering feature and why it does not work correctly anymore after the update of Android to version 4.4.
Applies to the following Sophos product(s) and version(s)
Sophos Mobile Security
Sophos Mobile Security - spam filtering feature and Android 4.4
New Default SMS app feature introduced with Android 4.4 breaks Sophos Mobile Security (SMSec) spam filtering feature
Android offers apps the functionality to read and write SMS and MMS messages on the device (using the "Telephony content provider" and the "SMS Provider”). As of Android 4.4 this functionality changed and the user now can select a "default SMS app”. Once selected, only the default SMS app is able to send SMS (on behalf of all other apps). In addition, the default SMS app exclusively receives an SMS before all other apps registered for receiving SMS. The default app is responsible to hand over the SMS to all other apps which should receive them.
What happens when Sophos Mobile Security is not the default SMS app?
If Sophos Mobile Security is NOT the default SMS app the SMSec spam filter is not able to stop the distribution of unwanted SMS to SMS apps. SMSec cannot delete the SMS from the device.
Note: The Loss and Theft feature is still functional (as long as a default SMS app does not prevent a command SMS).
Can Sophos Mobile Security be the default SMS app?
This is not possible.
Registering Sophos Mobile Security as “Default SMS app” practically does not work because other SMS apps would have to implement the required functionality to correctly interact with a different default SMS app. As of now, most of the standard SMS app do not implement that functionality.
Furthermore, the new Google Hangouts app is now also the standard app on Android 4.4 for handling SMS. Hangout requests the right to be the default SMS app every start if it is not configured as default application, yet.
What is the implication for the spam filtering feature of Sophos Mobile Security?
Starting with Android 4.4, the filtering of SMS in the SPAM protection will not work anymore. As of SMSec 3.1.1245 the feature is deactivated and the user gets an information toast when trying to activate the feature.
Note: All other features of the Sophos Mobile Security spam filter like call filtering still work.