Discriminator and FSK: ripping apart pagers?

[fog]

Okay, bear with me, because I worry this might sound insane for a second.

A year or two ago, I bought a set of old ATI Corporate pagers. Some worked and some didn't, and most wound up sitting in a box unused.

Lately I've become interested in trunking, specifically trying to get something like Trunker to work on a local EDACS system. 9600 bps FSK doesn't work coming out of the headphone jack.

By dumb luck, I stumbled across this guide: http://www.discriminator.nl/ccf-6000/index-en.html

It's about cannibalizing the model of pager I happen to left over (on the right band, even!) to grab the data off of its "FSK Out" pin.

Even though I'm handy enough with a soldering iron, I'm admittedly too dumb to grasp exactly what this is doing. Is this a conventional discriminator tap, or is the IC actually acting as a data slicer?

Thanks in advance for the help!