BT male plug to RJ45 female socket converter. This adaptor can be used to connect BT telephone lines to CAT5/RJ45 cabling. A BT 431A plug connects to the telephone line, at the other end is an RJ45 socket which accepts any standard straight wired CAT5e/RJ45 patch lead. This adaptor is wired for our master RJ45 male to BT female converters (also available-see below), simply plug one in at the other end and connect a telephone, Fax machine etc. An alternative to our BT to RJ45 patch leads. A version wired for secondary converters is also available.