Halp for Microsoft Teams - An internal help desk built into Teams

Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.

Roby - Refreshingly simple helpdesk for Slack & Teams users

Chatra - Live chat software that helps to increase revenue and collect feedback providing an easy way for website owners to talk to visitors in real time.

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

Chatlio - When you have a business to run, your average instant messaging software just will not do. You need an internal presence upon which your entire team can collaborate on. Read more about Chatlio.