We were wondering about what it takes to talk digital HT to HT without a repeater or hot spot. Turns out, brands and code plug formats don't matter. It seems you need to pick the same Tx / Rx frequency, Digital channel, Simplex, Slot 1, Color code 1, Tx authority: Always and Talk group 99. Maybe it would still work with different Slot, Color code and Talk group settings as long as everybody has the same settings. But these seem to be the popular ones everybody uses.
We ran a test today with me, K2BHM, Guy, KD2TLF, Mark, WA2NYY, and Bill, KD2UEN as a witness. 3 different brands with 3 different code plug formats all worked good together! Now that we know these parameters work, we can test at greater distances to see what influence location, power level and antenna has.
Jim Albrecht K2BHM