To work simplex with your DMR or C4FM radio please do not use the FM analog national call frequencies 2m (146.520 MHz) or 70cm (446.000 MHz). … DMR or C4FM Simplex Frequencies. ChannelFrequencyAdmit Criteria (DMR only)1 (UHF)441.000 MHzFree or Always2 (UHF)446.500 MHzFree or Always3 (UHF)446.075 MHzFree or Always4 (UHF)433.450 MHzDMR or C4FM Simplex Frequencies. – 0x9900 0x9900.com › dmr-or-c4fm-simplex-frequencies