  We study the connection between the BCS pairing model and the inhomogeneous
vertex model. The two spectral problems coincide in the quasi-classical limit
of the off-shell Bethe Ansatz of the disordered six vertex model. The latter
problem is transformed into an auxiliary spectral problem which corresponds to
the diagonalization of the integrals of motion of the BCS model. A generating
functional whose quasi classical expansion leads to the constants of motion of
the BCS model and in particular the Hamiltonian, is identified.
