I was recently hired to work for a small company that has about 80 users on a domain. I would like to setup a Skype for Business server to replace the aging Pegasus email system they use for internal communication since their licensing is running out soon. What I do not understand is the CAL licensing and how it would work. From what I understand I believe they already have licenses for their users to access the domain controller. Would we need to purchase additional licenses to run a separate Skype for Business server? I have little to no experience working with CAL licensing so any help would be greatly appreciated. Thank you.