The machine is initially set to Normal, which lets the machine connect to a standard PSTN (Public Switched Telephone Network) line. However, many offices use a central telephone system or Private Branch Exchange (PBX). Your machine can be connected to most types of PBX. The machine’s recall feature supports timed break recall only (TBR). TBR will work with most PBX systems allowing you to gain access to an outside line, or transfer calls to another extension. The feature works when Tel/R is pressed.