Explain the main part of configuration of a step by step switching system with the help of a neat diagram.

Configuration of a step by step switching system:

A step by step switching system may be constructed by using two motion selectors or uni-selectors uni-selectors or a combination of both. Here the wiper contacts of such selectors move in direct response to dialled pulses or another signal like off hook by the subscriber telephone. This wiper steps forward through one contact at a time and moves through as various contacts (takes as several steps) as the no of dialled pulses received or as needed to satisfy specific signalling conditions. Therefore the name step by step switching is specified to this method.

Three major parts has a step by step system that demonstrated in the figure:

1. Line Equipment part: This comprises selector hunters or line finders that represent two fundamental ways wherein a subscriber gains access to common switching resources. Firstly, a selector hunter searches and seizes a selector by the switching matrix part. There is one selector hunter for each subscriber. Line finders are connected with the first set of selectors in switching matrix part and here is one line finder for every selector in the set. By the name implies, a line finder searches and gets the line of a subscriber to be associated to the first selector connected with this.

2. Switching matrix part: This comprises one or more sets of two motion selectors termed as first group selectors, second group selector, and all that. The larger the exchange size, the larger the number of group selector stages.

3. Connector part: This consists of one set of two motion selectors termed ass final selectors.