Margo,
My name is Jim Sarris and I'm a high school Spanish teacher. I have tried to get my school to authorize Skype but so far they won't do it. I have used Tokbox but it was a disaster in the end.
However, I have created a web resource that I use with my students when they speak. It may be something you can use with your students.
If you'd like it's at the website. www.speakaforeignlanguageeasier.com
I would love to get your comments on what you like and how to improve it. You just need to sign up and take a look. No cost.
There is a video on the getting started page which will help.
Anyway, is you get a chance I would love to know what you think.
All the best,
Jim