For our company communication with our clients we are using ticketing system Zendesk. I must say zendesk is a great solution that is very modern and fast, it comes for the with the integrated chat and phone as well.
We were looking for a solution where we will have a ticketing system for the internal infrastructure, because over the years we grew a lot and now we have few system engineers that are maintaining internal IT for the test systems for our developers. The Zendesk was great, but we are using SSO with it so in order to open ticket for the internal IT some people would need to logout from one zendesk system and then login to another via SSO or not SSO so that would possibly cause a huge mess. So we decided to look elsewhere.
What I found is great zendesk competitor Freshdesk which is free for unlimited agents in the basic edition:
Freshdesk is free and really easy solution that from now on we will use for internal IT needs. What is the best on the end not only freshdesk is free but the Single Sign On integration with Azure is free as well. Here is the tutorial on how to configure freshdesk to work with your existing Azure subscription so users can authenticate thru Azure Active Directory. Awesome stuff, great work guys!