First you will need electronic training from somewhere, tech school, college or the military...once you get a basic electronic background you can then get trained on something more specific, ie cell phones, pc's ..I install and maintain key systems and pbx's which are now almost all I.P. based, even the smaller key systems we put in....but i got my start with oscopes and meters, electro mechanical swithches back in the early to mid 80's in the Air Force.
Most companies , after you get your basic electronics schooling will train you or send you to their school to work on their stuff.
