Push-To-Talk (PTT) / PTT-over-Cellular (PoC)

[Jan Kratochvil]

Hi,

anyone aware of any FOSS solution for:
        Push-To-Talk (PTT) / PTT-over-Cellular (PoC)
? According to:
        http://www.openmobilealliance.org/release_program/poc-v1_0.html

Thanks,
Lace