Both P25 and DMR are open standards, the only closed part is IMBE (which I believe is patent free now) and AMBE+2 (which will be patent free in the next 5 years

Both P25 and DMR are open standards, the only closed part is IMBE (which I believe is patent free now) and AMBE+2 (which will be patent free in the next 5 years). DSTAR is also a open standard too, but I think only has a single implementer, same for C4FM.