Security forces PMR networks are moving from proprietary technologies for their "Mission Critical Push-To-Talk" basic service, and their data services which must provide large bandwidth real-time access, to the databases. LTE Based is adopted with backup access to public MNOs to complement their own radio coverage. Specific technologies such as multicasting of visio are required so the MCPTT works within a restricted bandwidth. The need to be able to change the main MNOs to provide resilient coverage requires specific choices of SIM cards, with OTAble security domains. Practical LTE Based...