It seems even Cisco can't answer this one.
I have BE 7.0(2) - with my CUWL came Presence 7.0.(3)
The Presence HW docs state that the 7816-I4 and H4 Servers are not supported for this version of presence.
Cisco have discontinued the H3 and I3 models.
So - which one can I buy that will work with my version?