We have it installed at a couple of sites.

It is a trunk based recorder, it can't record the handsets.

It will record ISDN PRI, ISDN BRI, Analogue trunk (PSTN, POTS), and SIP.

I have a site with PRI, BRI and SIP and it's ok.
I have a site with PSTN and it works, you need caller ID on the PSTN lines though.