Can the helpdesk have multiple client interfaces?
Every customer has its own credentials that he uses to access the Help Desk through his/her web browser. At login he/she can see only their incidents and not the issues from other companies. However, if you would like somebody to have a possibility to see other incidents you can also set this up by modifying the permissions in the Administration Desktop. So this all depends on your needs, using Roles you give different permissions to each group. If you would need some help in setting this up to tailor your requirements please let me know and I will be happy to assist you.