Do you have a class blog using Blogger, WordPress, Weebly, Tumblr or Joomla? If you do, SpeakPipe is a cool way to connect with your readers. SpeakPipe add a "Send Voicemail" tab to the side of your blog that readers can click to record a voice message to your class. The free plan allows you to receive up to 20 voice messages a month (90 seconds max per message).
To get started, just go to https://www.speakpipe.com and create a free account. Choose your blogging platform on the setup window and it tells you exactly what to do to put it on your blog. Very cool!