Mission Critical Push to Talk (MCPTT); Stage 1
The present document provides the service requirements for operation of the MCPTT Service. MCPTT makes use of capabilities included in Group Communications System Enablers and Proximity Services, with additional requirements specific to the MCPTT Service. The MCPTT Service can be used for public safety applications and maritime safety applications and also for general commercial applications (e.g., utility companies, railways and maritime usage). The requirements in this specification do not apply to GSM or UMTS.