I made my first Google Gmail call yesterday to test it out. I have had a Google Voice account for some time now. Yesterday's call worked just fine. From an educational point of view it puts a phone in every classroom. But after thinking about this further, I wonder how many teacher computers even have a microphone let alone a webcam! Here are more ways to take advantage of free calling in gmail.
Get Caller ID from Your Computer
Transfer Calls to (and from) Your Computer to Save Cellphone Minutes
Find Your Misplaced Phone
Use It for a Quick-and-Dirty Speakerphone for Group Calls
Make a Quick Followup Call in Response to an Email
Secretly Record Calls
Make Free Calls Anywhere You've Got Free Wi-FiRead more at lifehacker.com