SHOT-D4 is a special O/E terminal equipment used for the transimission between SPC S1240 central office and RASM（remote terminal）

which can provide transmission path for the two subscriber distribution frames（i. e. 2 000 lines）. When the communication capacity exceeds 2 000 lines

a larger capacity communication system can be established by the way of building block systems. Furthermore

by using this equipment

the subscriber distribution frame can be easily removde out of the office and used as RASM without the additional investment for switching equipment.