Since I don't have the time to create my own tutorials, here are some nice web sites that you may find helpful if you are a novice or even a seasoned engineer when it comes to understanding the technical aspects of telephony and electronics:
http://www.electronics-tutorials.com/basics/basic-electronics.htm - Basic Electronics
http://www.101science.com/Radio.htm - 101 Science - Electronics
http://www.iec.org/online/tutorials/fund_telecom/ - Fundamentals of Telecommunications
http://www.ssg-inc.net/telco.htm - Telecommunications Tutorials
Telephone Technical Links - One of my web pages with more links of the technical nature.
For a glossary of common terms used in these fields, click HERE.