Mission Critical Push-to-Talk (MCPTT) is a vital element of future LTE-based critical communications systems. The industry has made tremendous progress producing clients and systems that work. But effective direct device-to-device communications is an extraordinarily important requirement that remains out-of-reach. With the clock ticking to shutdown of its legacy emergency services PTT network, the UK is now forced to embrace a "Plan B". Is this the answer for the rest of the world?