Setting up a DMR Hot Spot involves choosing a hot spot frequency in the 70 Centimeters Band [420-450 MHz]
A radio frequency band plan is a voluntary division of a band to avoid interference between incompatible modes.
One of the goals when choosing a hotspot frequency is to avoid interfering with other bands such as:
432.000-432.070 MHz [Earth-Moon-Earth];
435.000-438.000 MHz [Satellite Only (internationally) and,
446.000 MHz [National simplex frequency]
Here is a link to the American Radio Relay League’s detailed Band Plan information page: http://www.arrl.org/band-plan,
I use the frequency of 433.000MHz for one of my hotspots which is included in:
432.400-433.000MHz [Mixed-mode and weak-signal work] and,
433:000-435.000MHz [Auxiliary/Repeater Links]
I use 427.17500 and 427.07500 for my hotspots.