At my first company, I was thrown in the deep end of having to do cold calling, and it's amazing how simple pitches you can get away with if your product is actually something people see value in, and you sound genuinely interested in providing value.

I also think this is severely under-utilized. Especially since you can often get hold of people on the phone that you'd never get an e-mail reply from, if you're just friendly but persistent with assistants etc..

I'm in the same situation as you with respect to being an introvert. It was agonizing work, but it also drove a significant portion of our revenue. An alternative if you can afford it is to talk to a professional lead generation company (though be careful that they reflect your brand well - this is one of those areas where it definitively does not pay to skimp and end up with some cowboy). The downside of the latter even if you find a good agency is that nothing beats getting direct feedback on what is right and wrong with your pitch.