There are cases where both a Sales rep and a Customer Support agent will need to be assigned to a Contact. When a customer have questions that the Sales reps are unable to answer, the Customer Support agent is able to jump in to help.

You can assign one user per Contact as the main contact point for customers. However, by introducing "collaborators", users can also be assigned as a collaborator to support the assignee if needed.

Only one user can be assigned to one Contact.