There are a number of services that are totally free (for basic use) and may suit your needs.
We highly recommend the following WEB BASED tools:
Google+ Hangouts - https://plus.google.com/hangouts
Requires a Google account. Google's chat network lets you send and receive instant messages with friends, family, and colleagues. Exchange real time notes and emoticons with anyone on the network using Google properties (i.e. Gmail, iGoogle, orkut, Google Talk, Google+) or a third-party client.
- All students and adjunct faculty have access to Google+ via their mail.immaculata.edu account.
Get a group of people together on one call. You can add up to 25 people. You can share a group call with up to 25 people, anywhere in the world, and if everyone’s on Skype, it’s completely free. If you’re calling people who are on a mobile or landline, you’ll need a little Skype Credit or a subscription.
FaceFlow - http://www.faceflow.com/
Offers quick and easy video chat rooms for free.
- See video, http://www.youtube.com/watch?v=Xi3caOmeYik
There are also options for tools that you can install locally:
Skype - http://www.skype.com
Skype is the original big name in online calls, the free version of this software allows you to make Skype-to-Skype calls, video calls, Instant messaging, and screen sharing
VSee - http://vsee.com/site/ (Windows Only)
VSee's is a free video chat tool as well as a collaboration tool. You can collaborate with a colleague on a document even if that person doesn't have the software installed through screen sharing, and you can share that file by dragging the file onto your chat video. The free version supports video chats with up to four people simultaneously.
Facetime - https://www.apple.com/mac/facetime/ - (Apple Only)
Face Time is the default video messaging application bundled with Mac OS X and iOS.