  We discuss the effects of anisotropy on superconducting critical temperature
and order parameter in a strongly coupled regime. The multiband representation
is used as a model for anisotropy. We show that strong coupling effects in
multiband superconductors lead to pair-breaking due to interband coupling
because soft phonon modes play the same role as usual impurities. This effect
makes the order parameters in different bands equal to each other and limits
the upper bound on critical temperature.
