TETRA is not a Motorola Standard, nor particularly secure
Contrary to what many believe, TETRA (formerly known as Trans-European Trunked Radio) is a Open Standard and is primarily hawked around the place by EADS / Cassidian and Motorola.
It is proclaimed to be secure but at a recent symposium held in China I saw an interesting combination of a SDR (Software Defined Radio) coupled to a TETRA hacking computer which output intersting data, for those interested, DMO gateway functions, short data services (SDS), packet-switched data and circuit-switched data communication, etc. I was unable to understand the audio as I am not that fluent in Mandarin.
One hundred and twenty plus countries have some TETRA systems. In VietNam there is a 3-base station system for Internal Security and the Peoples Police in the country's largest city, Ho Chi Minh, running over Motorola equipment but when I have monitored it is hardly active since the police prefer cell handsets! The Peoples Police (Cong An) spend most of their working hours 'patrolling' their offices seated sleeping in chairs which obviates the need for mobile communications.
BeiJing, a hot spot for high-tech Plod communications uses a custom-built system with handhelds having swipes for ID cards and large display screens.
Smartphones likely could provide similar services in most cases.