A、Integrating software with traditional telephone. B、Combination of computer and telephone. C、Software application with Internet

The growing phenomenon of people who are making cheap or free long-distance calls over the Internet, particularly in China,[20]is forcing phone companies around the world to rethink how they should charge for similar services. Internet Protocol Telephony, or in other words the IP phone, is the key issue facing policy-makers, regulators and the industry. Internet Protocol Telephony-the technical term for Net-based telephone and data services-is rapidly changing the way people communicate.
    Use of the Internet for voice messages started around 1994, when it became possible for computer users to talk to one another, provided that each had the same software and logged on at the same time. Advances in technology by 1996 made it possible for a PC user to call a regular telephone user. By 1997 phone-to-phone Internet had become possible. The traditional phone companies are eyeing a market of more than 1.5 billion phone, fax and cell-phone users worldwide. Telecom providers continue to use traditional telephone networks for most long-distance calls, but International Telecommunications Union research shows rapid growth over the Net: from no significant international telephone traffic in 1997 to over 35 per cent by 2002.[22]It’s a technology that undercuts the pricing policies and business models of existing operators. Price and cost savings are forever driving the market.
20. What forces the phone companies to rethink their charge for phone service?
21. What made it possible for computer users to talk to each other?
22. How does the Internet Protocol Telephony influence the telephone industry?