The DSM303 should be compatible with all models of Sepam 20, 40, 60, and 80. Normally, if the customer orders a new DSM303, it will be compatible with all Sepam. But, if it is an old DSM303, maybe ordered before 2000, then it may not be compatible with the Sepam specially with series 40. DSM has its own firmware, in which we have zero access. If the firmware of DSM303 is less than V0146, then there will be a problem. DSM303 cannot have firmware upgrade, it should be replaced.