Line Adaptors ISDN Master Tailed Line Adaptor PABX Master Direct Fit Line Adaptor PABX Master Tailed Line Adaptor PSTN Master Direct Fit Line Adaptor PSTN Master Tailed Line Adaptor Secondary Direct Fit Line Adaptor Secondary Tailed Line Adaptor Switchable Line Adaptor - Direct Fit Switchable Line Adaptor - Tailed