What is 100 line exchange with one two-motion selector per subscriber.

Design: In, Strowger switching system is designed by using one two-motion selector for all subscribers. A subscriber is allocated a number in the range 00-99, and similar number is used to specify the two-motion selector assigned to him. The 100 outlets of each two-motion selector are numbered according the scheme specified in table. The equivalent outlets in all the 100 two-motion selectors are commoned and folded back to the equivalent inlets. For illustration, a subscriber with 87 as his number is assigned the two-motion selector 87. The outlet 87 that corresponds to this subscriber is associated to the 7th contact in the 8th vertical position of all the two-motion selectors and folded back to his inlet. The arrangement is demonstrated in figure. If subscriber 23 dials 87, his two motion selector 23 would step vertically 8 times equivalent to the first digit and would step horizontally 7 times to reach the contact to which the subscriber 87 is connected. This switch is non- blocking and uses only one stage of switching components. Because the two-motion selector is activated through the calling party, the call is terminated only while the calling party disconnects the line. When a two-motion selector goes out of order, the subscriber connected to this will not be capable to make any outgoing calls but can get incoming calls. The design parameters of such switch are:

S =100, SC =50, K = 1, TC =1, EUF = 0.5, C= 200, CCI =25, PB =0.

FIG - 100-Line exchange with one two-motion selector per subscriber