single frequency

Hi all, was't sure where to post this, so if this is the wrong place, please forgive... Recently came across a Single frequency dmr channel in my area, when I ran it in DSD plus it seems it says "XPT" in the event window, however, it seems that all control, data, and voice flow over the same...

Can a single frequency (vhf or uhf) that is using P25 only use phase 1? or...Can they optionally use X2 or phase 2 on the single frequency? I always hear/read about X2 and phase 2 as it relates to trunking, but was just curious how this might/could work with a single frequency using P25?