Jettasback- my guess is it has to do with the trading permissions set up by TD Ameritrade, for some brokers when buying penny stocks you need to do it through a broker (im assuming they use the cover of explaining to you that buying pennystocks is risky and so figure by having a person speak with you they may be able to provide you with the necessary caution). Long story short, I have interactive brokers and have no issues with purchasing CCTC.
You probably know this already that buying stock via phone the commission is going to be larger so you need to factor that cost into your investment i.e if your going to buy $100 worth of stock and their commission is 15-20$$ that means the stock has to increase 15-20% just to cover your costs of investing. Obviously the larger sum of $$$ you invest in a single block the percentage is going to reduce.
DISCLAIMER: I AM NOT A BROKER NOR A FINANCIAL ADVISER SO I WOULD CHECK WITH SOMEBODY LICENSED TO VERIFY WHAT I AM SAYING