Yaar I can't guide you much coz I m a software engineer just by chance i never thought of being one.....
I Just applied in company requiring fresh graduates and I only knew that this company works on voip..... so they selected me trained me on .net and made me a software engineer... now I do programming for different servers......
its neither main stream software nor main stream telecom but still it's quite important coz
we are basically working on products for call centers....
main stream software is I guess web based now...