After a long time since its birth and promising rise, IMS seemed to be a dead technology, buried due to the success of mass market proprietary alternatives for VoIP and Instant Messaging.
However, out of the sudden, VoLTE, MCPTT and IMS based eCALL seem to have brought undead IMS back to Life in citizens-to-authorities, first responders and eCALL relevant areas.
Mission critical communications standardization process began in early 2015 with the creation of SA WG6 – Mission Critical Applications. Initially this working group has been focused on the definition of the functional architecture and the information flows of Mission Critical Push-To-Talk (i.e. MCPTT). About a year later 3GPP practically finished the standardization process and launched MCPTT Rel.13 after the SA#71 plenary meeting, which was held in Gothenburg in March 2016.
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