I know this is an older thread, but hopefully this helps people who are still looking, like I was. It looks like it's a setting for the scanner as a whole, not sure if it can be changed per site or not. That isn't an issue for me, as I am using the unit in my home and not moving around with it. I know this information was kind of said before, but I thought I might help in clearing it up a bit.
P25 Threshold (996P2 only) this is a hidden setting accessible only by turning off the radio and pressing and holding the Hold/Resume button while you turn the scanner back on. The scanner will go through all the lights when starting up. The feature will be unlocked in the menu under settings, called P25 threshold.
Here is the link where I found the info, it's also a really nice and organized manual:
Easier to Read BCD996P2/XT Digital Scanner Manual