There are a couple of things you need to figure out. First off you need to develop a business and marketing plan that will be unique and will be financially sound. The more unique the business plan, the more likely you are to attract investors. It is possible to start a business without significant differentors but you will most likely have to finance it yourself. Among many things, your business plan will have to have what you will be selling (PC to phone S/W, PC to phone service, etc), how much it cost to build, how much people will be willing to pay based on market research, how you will sell it and many other business issues. The plan will need to address the Four P's (i.e. 4 P's) Price, Product, Place, and Promotion.
Secondly, you need to determine how you will finance your plan. The two primary methods to start a business like this are either to self-finance it or get Venture Capital (VC) funds to finance it. If you don't have a plan that is unique and financially sound, it will be extremely difficult to get VC funding. Most VC funds are focused on existing investments are not looking for new companies to finance. If you self-finance you will have to have the necessary savings and a business plan that is very conservative, grows very slowly initially and becomes profitable very quickly.
The U.S. Government Small Business Administration has a lot of good information to help you get started. http://www.sba.gov/starting/indexbusplans.html
This was first published in December 2002