It is listed as digital in their station. As many of you scannerists know the cops are not the best place to get correct info.
XTS &XTL 2500's have the ability to do ADP and with the proper module DES XL or DES OFB. This is coming to a location near you btw.
They would have to buy an APCO 25 repeater or base made by several companies not just Motorola before they could use digital APCO 25. Some radio shops are doing their best to sell Motortrbo to public safety as a cheap way to hide. The shops are desperate in these econonmic times to sell anything.
There is also the NXDN brand of digital not popular in this area but in some parts of the country they have bought into it.
And then of course you have the drop in aftermarket modules or simple voice inversion like River Vale has.
It's all part of the Northern New Jersey lack of interoperability with unlicensed channels and no cooperation.
Probably inversion scrambling. I'm thinking when you say Closter you mean Westwood who is on 154.9500 023 as their F9. I have a few private channels from that area that I hear chatter on from time to time. Only thing to do is search 150-158 mhz band or sit in Old Tappan next time you are there with closecall. I highly doubt they are using APCO25 or encyrption. Most of those towns have CDM1250s and HT1250s or Kenwood TK790s. Don't know of many with Motorola XTL2500 digital capable radios.