Tips on career migration

I am interested of changing field. Telecommunication (pure voice) would be my new concentration but I do not want to jump on such pool if I am not well oriented with it.

So I am looking for your tips on how and what should I tackle first prior proceeding to telecommunication field.

I have backgrounds of telecommunication but all of those were shool-based theories. Could anybody provide an enthusiatic websites, books on how to deal with this.

Such term as X.25, Frame Relay and other related telco terms is like a strange word to me because I am a newbie in Telco.

Looking forward for any reply for those sympathises newbies.

Thanks and more power to techrepublic.