  We compute the full one-loop 2-particle S-matrix for excitations of the type
IIB AdS(3) x S(3) x T(4) BMN string. The S-matrix is found to respect the
expected symmetries and the phases are consistent with the crossing equations.
By analyzing how the relevant integrals scale with the IR regulator we show
that scattering of massless bosons is trivial at two loops. Based on our
results we argue that the additional su(2) S-matrix appearing in the massless
sector in the exact solution should trivialize.
