Aerospace company Boeing stabs at the ultra-secure smartphone arena with the Boeing Black-- an Android device so paranoid the data it carries self-destructs should someone tamper with it.

As a Boeing patent puts it, "any attempt to break open the casing of the device would trigger functions that would delete the data and software contained within the device and make the device inoperable." Just like any phone fit for a spy (or the set of TV's Person of Interest), then.

Further security features inside the Black include storage encryption, a hardware root of trust and a hardware crypto engine. It is also modular, allowing users to integrate additional functionality such as biometric sensors or satellite connectivity.

Panasonic might be out of the consumer smartphones, but it continues making enterprise devices-- the company uses Mobile World Congress 2014 to reveal a pair of Toughpad-branded smartphones.

The devices are identical in look, with 5-inch displays and rugged 3cm-thick casing. One runs on Android and the other on Windows Embedded. Both promise water resistance, survival from falls of up to 3m and capability to operate in temperatures ranging from -20 to 60 degrees celsius.

Inside the rugged casing are either 2.3GHz quad-core Qualcomm Snapdragon 800 CPU (Windows Embedded) or 1.7GHz Snapdragon S4 (Android), as well as a 8MP rear-facing camera. The harware buttons are rubberised, while the casing features modular components users can unscrew and swap out.

Customers wanting to shield communications from the NSA and its spying ilk might be interested in the Blackphone, a smartphone armed with a security suite appealing to more paranoid users.

Launched at Mobile World Congress 2014, the Blackphone is a collaboration between Spanish mobile maker Geeksphone and security developer Silent Circle. It looks like a regular 4.7-inch smartphone with a 2GHz quad-core processor, 2GB RAM 16G storage and an 8MP rear-facing camera but runs on "SmartOS," a modified Android version  promising to "keep communications private without extra effort."

Silent Circle provides a number of own security apps-- Silent Phone (provides peer-to-peer encrypted VoIP calls), Silent Texts (encrypted SMS) and Silent Contacts (contact list and call log encryption). All are subscription-based, with Blackphone users getting a 2 years for free.

Nokia confirms recent rumours at Mobile World Congress 2014 when it unveils the Nokia X smartphone lineup-- a trio of low-cost devices running not, as one might assume, on Windows Phone but Android.

The Nokia take on Android is nothing like that seen in devices from the likes of Samsung, Sony or HTC. Instead X smartphones carry a "forked" version of the Google OS, with a Windows Phone-style tile-based user interface and no support for Google-specific features such as Gmail or the Google Play app store.

User can get apps via Nokia Store, 3rd party app stores or even sideloading. The company also includes own and Microsoft services, namely HERE maps, MixRadio music streaming, Outlook, OneDrive storage and Skype.