  The homogeneous Lippmann-Schwinger integral equation is solved in momentum
space by using confining potentials. Since the confining potentials are
unbounded at large distances, they lead to a singularity at small momentum. In
order to remove the singularity of the kernel of the integral equation, a
regularized form of the potentials is used. As an application of the method,
the mass spectra of heavy quarkonia, mesons consisting from heavy quark and
antiquark $(\Upsilon(b\bar{b}), \psi(c\bar{c}))$, are calculated for linear and
quadratic confining potentials. The results are in good agreement with
configuration space and experimental results.
