Coloured lines are used represent the type of premises wiring as indicated below.

Standard twisted-pair telephony cable.
A network (Cat-5 or Cat-5e or Cat-6) cable.

The majority of telephone premises-wiring uses star-wired  or parallel-wired configurations. In a star-wired configuration the telephones are all wired back to a "master" socket or distribution box. In a parallel-wired configuration, the cable run passes sequentially from socket to socket at each telephone.

Star-wired configuration	Parallel-wired configuration

Note: In any of the drawings in these reference pages, any analogue telephony device (fax analogue modem, answering machine, alarm unit, etc) can replace any telephone.