If your laptop has a microphone, speakers and keyboard to dial the number, why not use it as a phone?
That's only necessary to solve the problem of software and connection method.
Regarding the method of connecting all enoughplain and simple - the presence of an internet connection solves this part of the question. And, it does not necessarily have to be "attached" to the ISP cable, stretched in the home or office. You can use the Internet via wireless protocols EDGE, 3G, Wi-Fi and WiMAX. EDGE and 3G modems can be purchased in almost any interior cellular. Operators providing Internet services at relatively low prices, offering special sets of equipment with beneficial tariff plans.
Moreover, in commercially available modems 4G (WiMAX),Hotels with internet connection at high speed. Such modems are part of the pre-installed equipment in some models of laptops. Wi-Fi protocol supported by all modern laptops, but unlike EDGE, 3G and 4G modems to connect to the Internet you need to be near a working access point.
Regarding applications that can help youto make voice and video calls, but now most of the popular ICQ-client offer such an opportunity. For example, to make free calls to each other using a laptop and internet connection, you can use the application ICQ, QIP, Mail.ru Agent and other similar programs. If you have a webcam laptop (it can also be purchased separately), your mobile computer can be used for video calls with the help of the same programs.
Alone among applications, allowing to makevoice and video calls, Skype is a program. After installing the program, registration in the system and replenishing the account by credit card or electronic money you can make calls from your laptop to mobile and fixed phones, as well as make long-distance and international calls at very competitive rates, which does not provide any fixed telephone operator.