  SPI, the Spectrometer on board the ESA INTEGRAL satellite, to be launched in
October 2002, will study the gamma-ray sky in the 20 keV to 8 MeV energy band
with a spectral resolution of 2 keV for photons of 1 MeV, thanks to its 19
germanium detectors spanning an active area of 500 cm2. A coded mask imaging
technique provides a 2 deg angular resolution. The 16 deg field of view is
defined by an active BGO veto shield, furthermore used for background
rejection. In April 2001 the flight model of SPI underwent a one-month
calibration campaign at CEA in Bruy\`eres le Ch\^atel using low intensity
radioactive sources and the CEA accelerator for homogeneity measurements and
high intensity radioactive sources for imaging performance measurements. After
integration of all scientific payloads (the spectrometer SPI, the imager IBIS
and the monitors JEM-X and OMC) on the INTEGRAL satellite, a cross-calibration
campaign has been performed at the ESA center in Noordwijk. A set of sources
has been placed in the field of view of the different instruments in order to
compare their performances and determine their mutual influence. Some of those
sources had already been used in Bruy\`eres during the SPI standalone test. For
the lowest energy band calibration an X-ray generator has been used. We report
on the scientific goals of this calibration activity, and present the
measurements performed as well as some preliminary results.
