The Internet is a great big data pipe that can carry a lot of things, including phone calls., then come back here to learn how to use your computer as a phone.
Assuming you have a computer, you'll need three things: the Net, some software, and some hardware.
First the Internet connection. The higher the speed, the better. Unlike regular phone service, there's never a direct connection between you and the person you're calling. Like other Internet traffic, your call arrives in packets. The faster you can receive and send those packets, the fewer problems you'll have.
There's no end of voice over Internet Protocol or VoIP programs out there. The most popular is Skype at Skype.com. It's a free download and let's you make free calls to anyone else with Skype and charges for calls made to landlines or cell phones.
You can buy Skype credit and pay as you go or choose a plan. From the U.S., plans range from $3 to $10 monthly depending on what countries you want unlimited calling to. Plans include a phone number that any regular phone can call. You can also buy a phone number separately if you want to pay as you go for outgoing calls.
An alternative to Skype is Gizmo5 from Gizmo5.com. Similar to Skype, calls to other Gizmo5 users are free and you can buy credits for making calls to landlines and cell phones.
From the U.S,. rates are a couple cents a minute within the U.S. It costs more for calls to countries outside the U.S. and significantly more to cell phones outside the U.S. To receive calls, you have to purchase a call-in plan. The rates vary depending on what country you're in, the cheapest starts at $3 a month.
Both Skype and Gizmo5 feature text messaging, voice mail, conference calling, and call forwarding. Another cool thing is that both services work on mobile devices. Skype works on Nokia Tablets, the Sony PSP, and Windows Mobile devices. Gizmo5 works on Nokia tablets, BlackBerrys, and several other platforms.
The simplest, but maybe worst, is a microphone and speakers. Most laptops have these built-in but watch out for feedback.
The next step up is a headset with the mic built-in. In fact, some may consider this ideal, although it is tethered to your computer.
Ideally, you can get a VoIP handset that looks and works like a regular landline phone. Skype has the edge here, with several VoIP handsets built specifically for their service. There are even a few that work with VoIP and a regular landline. One of those is even called the iPhone. So you can brag that you have the original iPhone (from Linksys).
One key thing to remember before you go dumping your landline is that most emergency services are not accessible from these services. For instance, 911 is not available from Gizmo5 or Skype in the United States. For that level of service, you need to subscribe to a specialized VoIP service as provided by many cable companies as well as phone services such as Vonage.
However, with that one important exception, you can otherwise use your computer just like a telephone.