Yes, teachers and students must include a Skype account in their profile in order to schedule live sessions, although they can use other tools if they want. Skype is integrated into the site as the default video conferencing tool. For your privacy, your Skype account is not public on the site. Here are the steps to add your skpye account:
Go to your profile
Edit the "Personal Details" section
Add Your Skype Name (the last field on the page)
Click On "Save"