The first program we tried is called Tribal Voice PowWow . It is available for free download on the Web. You can speak with this program and also have a simultaneous written chat. Other features include sounds and a whiteboard. Full duplex is more like a standard phone conversation.
Some days are better than others for telephony.
As it turns out, PowWow is the only program I actually brought into the classroom. The others I tried have an adult edge to them. PowWow is the cleanest and the safest I've found. Other choices are PhoneFree , another free download, and Internet Phone by VocalTec. Internet Phone comes with a second user license, voice mail, and various bells and whistles, including free video upgrade, so you can talk and see the other person.