What are some alternatives?
Taiga - Project management platform for agile developers & designers
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
TargetProcess - Agile Project Management Web Application
ZenDesk - Zendesk is a beautiful, lightweight help-desk solution.
Eylean - Eylean is an Agile project management software for teams looking to visualize and enhance their project process.
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.