Coupled channel formalism for unequal masses of interacting mesons has
been developed using the separable interactions. The scattering ampli
tudes and the corresponding channel integrals have been calculated. A
practical method to determine the potential parameters from the positi
ons of resonances in the complex energy plane has been formulated. The
two-channel formalism has been extended to three interacting channels
. A useful parametrization of the 3 x 3 S-matrix in terms of phase shi
fts and inelasticity parameters has been written.