This is why you want to do a business plan, because you want to answer this question for yourself before you get started. Has anybody else done such a hotline business in Austria? Are you aware of that kind of business in any other country? If so, research that business, look at its website, call it, call the people who run it, find out as much as possible about it. And if not, if nobody seems to have done this before, it still might be a good idea for a solid business but you're going to have to do more guessing. Find out all the costs, and estimate how much people will pay per minute for conversational English. You won't be able to know for sure, but you can make an educated guess based on what customers pay per minute for other non-sex phone services. Think about who your customer would be. Who are they, where do they live, what media do they use for information, how much might they pay. Then investigate the costs. Get the information from the phone providers who offer the per-per-minute phone services. How much will you pay per minute? How much more can you charge than what you will pay, per minute. These are the kinds of questions you'll want to answer before you move forward.  I know I'm not answering your question, but knowing the answer is at best an educated guess and it is also something you have to investigate, meaning work, and you have to do it. You have a lot to gain if it works, and, depending on your plan, a lot to lose if you go forward and it doesn't work. Tim