Which stage 1 specifications specify the architecture and information flows to support Mission Critical Push To Talk (MCPTT)?
TS 23.280 and TS 24.481
TS 24.379 and TS 24.380
TS 29.213 and TS 29.214
TS 22.179 and TS 22.280
TS 23.379 and TS 23.280