The marriage of computer and telephone technology goes by the funny name of VOIP (Voice Over Internet Protocol). But the cost savings are no laughing matter.
The Simplest Solution -- Headphones
Attach a headset to your computer’s sound card and you can try VOIP for free!
Download any one of the many VOIP software packages -- Skype, Gizmo, Free World Dialup, and Net2Phone are some of the big names. Install and invite your buddies to install the same software. It’s that easy to set up. Special features like call display, call forwarding, voicemail, and conference calls are also free as long as both parties are using computers.
It's even easier to use. Just click on a name to start a call. Most of these so-called "soft phones" allow you to place and receive calls at no charge to and from anywhere in the world, so long as you are not connecting to cellular or landline phones.
Internet Phones
The next step up from headsets is Internet phones. They plug into the USB port or sound card of your computer.
Because you still need VOIP software installed on your computer to make and receive calls, these phones are also considered soft phones. But they seem more like "real" telephones because they ring, have regular number pads and are used like conventional phones.
Analog Telephone Adapter (ATA)
Progressing up the VOIP ladder, ATA is next. It allows you to connect a regular analog telephone to a broadband modem. It is usually free when you sign up with a provider, similar to signing up with a telephone company. There is a monthly charge for this service, and you may have to sign a contract committing you to that provider for a specified period.
Using an ATA for Internet phone - continued below ...