Google Voice

On Wednesday, the Web giant announced that American users of its Gmail Web service could call numbers in the United States and Canada for free from within their browsers. Calls elsewhere cost less than many traditional long-distance domestic calls: You pay 2 cents a minute to call Ireland, Korea, Argentina and many other countries. (Google's rates top out at 99 cents a minute for those calling the island nation of Nauru.)

The Skype Internet-calling service charges slightly more for international calls, but it also charges about 2 cents a minute for domestic calls.

Gmail's rates should be familiar to users of Google's free Google Voice service, a separate option that the Mountain View, Calif., company only opened to the public in June. But using Google Voice requires logging into a Web site or launching a program on your phone (if one is available for it) and, in some cases, waiting for Google to connect your call.

Calling from within Gmail, by contrast, requires nothing more than installing a small plug-in program (available for Windows XP or newer, Mac OS X 10.4 or newer and some versions of Linux) and logging into Gmail. Click the "Call phone" link to the left of your inbox, type in a number, click the big blue "Call" button and things proceed as if you had just finished spinning a Bell System phone's rotary dial.

If you have a Google Voice account, the other person will see that number in their caller ID. You can also answer their calls from within Gmail; an incoming call will generate an alert in the bottom right corner of the Gmail window, which you can click to answer.