South Korean operator SK Telecom and Nokia have jointly developed a ‘Mission-Critical Push-To-Talk (MCPTT)’ service, a push-to-talk communications technology over VoLTE. The two partners have also demonstrated the technology at Nokia's Research and Development Center in Krakow, Poland.
MCPTT is designed to enable communication among hundreds of rescue workers by using a dedicated channel at times of massive disasters. MCPTT uses the VoLTE network and supports a stable group communications service - even when there is a surge in users - through the application of Group Communication System Enabler (GCSE) based on evolved Multimedia Broadcast Multicast Service (eMBMS).
SK Telecom plans to use the MCPTT service for Public Safety-LTE (PS-LTE) and LTE-Railroad (LTE-R) in Korea and also expects to expand its reach to countries that are currently promoting the public safety network projects such as the US and UK.
Source: https://www.telecompaper.com/news/sk-telecom-nokia-develop-mcptt-service-over-volte--1180461