osTicket is an open source support ticketing system. It collects requests that arrive by email, web form, phone or API into one multi-user web interface, where tickets are saved, routed to departments through filters and help topics, assigned to agents and archived. It offers a customer support portal, dashboard reports and service level agreements tied to business hours. It runs on a standard web server with PHP and MySQL and is used for IT service desks, customer support and internal helpdesks. Its maker, Enhancesoft, also offers a hosted edition called SupportSystem and a virtual appliance.
The open source edition is free to download and is installed on your own server, so you decide where the data is hosted, including within the EU, and who has access to it. For the hosted SupportSystem edition, the vendor's pages do not state a data location, so ask before relying on it. Self-hosting gives a European organisation control over data and jurisdiction, at the cost of running, securing and patching the system itself. The commercial offerings come from Enhancesoft LLC.