1.) Electromechanical consists of  : space division switching and time division switching 

Electronics switching system consists of step by step system and  crossbar system

2.)Automatic switching system can be divided into two parts. They are :

# Electromechanical and 

# Electronic.

3.) Electromechanical switching system can be divided into two parts:

1.Steb - by - step  and 

2.Crossbar

4.) In space Division switching system, dedicated and exclusive switching path should be established.

5.) In time division digital switch can be designed by using a combination of space and time switching techniques