If you are talking about the JK Audio devices, I am certain that they should work on any common telephone, but understand that these devices install between the telephone base and the handset. Agents will know when they are being recorded.
To get around that, you would need to do something interesting, like set up service observing, installing the recorder on that telephone. You'll probably want to remove the mic from the handset on the phone so that you don't pick up any room audio on the recorder. You do not have to remove the mic to silently monitor the agent though, the switch hooks you up in simplex for service observation.
As far as attaching a recorder is concerned, that is what these things are designed for. I've even hooked them up as the mic input to a sound card and digitally recorded before.
pansophic