Not sure about cos, but room status (need cleaning, maintenance, check-in/out, etc)

Credit for phone calls as well.

Has a pms interface so this can be done by the software if it supports it, rather then via a keyset.

I have a document somewhere about the features and how-to use them. I think it even has the pms info in it.

Is written for the dcs systems but it's the same on the os (except it's now supported over ip rather then sio)