How Can I Use My Computer as a Telephone?by Steve McDonnell
Several services allow you to use your computer as a telephone by placing calls to other landline or mobile phones. Many of these services also allow you to place "computer-to-computer" calls by dialing another computer that is configured to receive phone calls, rather than dialing a telephone number. Some of the companies that provide these services charge for the capability, and some services offer free phone calls inside the U.S., with discounted rates for calls to phone numbers outside the U.S. To use your computer as a phone, you need to select a provider, download and install the provider's software, connect the headset and start dialing.
Select a service to use for making telephone calls with your computer. Visit the website, create an account if you don't already have one, download the software it provides and install it on your computer.
Connect the headset to the computer. Insert the audio plug into the computer's audio-out jack (usually green) and the microphone plug into the computer's microphone-in jack (usually pink). Put the headset on your head and position the microphone near your mouth.
Run the software program you installed. Click the "Call Phone" or similar button in the software and click or type the digits of the telephone number you wish to call. When the other party answers, conduct your telephone conversation as your normally would, using the headset earphones and microphone in place of a telephone receiver.
Click the "Hang Up" or similar button to end your call.