In the early days ....

phone switching was actual 'phone switching' ..

As a matter of fact, we still use the name 'relay' for a 'phone'switch unit.
These days we are used to 'hubs' and 'routers', etc ....

Contact erosion is and was a mayor problem.

You have cleaned all contacts between your mobile phone and your 'fixed' station.

Maybe you can design a 'full automated phone cleanup system' with a 8051.

Have fun.