Give this a try, this is from the KPG-111D, should be the same, or close enough, for the 720:
Under the Edit button on the top, select:
NXDN,
General 1 Tab:
Enter Unit ID (own) (range of Blank, or 1 to 65519)
Unit ID Name (own) can be used for vehicle ID for mobiles or badge number/ID for portables. (up to 14 characters)
You would need to click the Over-the-Air Alias button to make that work. Very nice function that sends the radio NAME out in the packet, so you don't have to program alias tables into all the other radios.
Group Call Display Type needs to be set to allow Calling Transceiver ID or Calling Transceiver ID/Group ID. This will allow calling radio ID number/name to show up on the other radio.
You will also need to select NXDN ID in the Optional Signaling (NXDN) drop down list in Zone Information window for the Conventional Group.
To send GPS data, you need to set the Base ID Type on the NXDN General Tab 1 to Unit ID. Then you enter the Base ID of the radio that is connected to the PC that is running the mapping software. There is a bunch of settings that need to happen to transfer GPS data back and forth, that is all included in the KAS-10 help menus.