  The Black Hole (BH) binary Cygnus X-1 has been observed simultaneously by
INTEGRAL, RXTE, and XMM-Newton for four times in November and December 2004,
when Cyg X-1 became first observable with XMM-Newton. During these observations
the source was found in one of its transitional states between the hard state
and the soft state. We obtained a high signal to noise spectrum of Cyg X-1 from
3 keV to 1 MeV which allows us to put constraints on the nature of the
Comptonizing plasma by modeling the continuum with Comptonization models as
eqpair (Coppi 1992). Using XMM-Newton we were also able to confirm the presence
of a relativistically broadened Fe K-alpha line.
