Telehealth services in the State of Pernambuco, Brazil are led by the Telehealth Center (RedeNUTES) and based on HealthNet 2.0 software. Among the tele-assistance services, health professionals have clinical discussions focused on second opinions. This paper reports the experience in a PhD study through mixed-methods, to evaluate the telehealth services, planning and modeling a new tool to improve a telehealth system. We described the nurse's role in each phase of this study. The method of User-Centered Design was explored in three phases as Identification of work process, User's perception and collaborative modeling, Observational usability study. The main frame was based on collaborative techniques as Collaborative Prototype Design Process, cognitive walkthrough, and thinking-aloud. The users also identified all usability problems identified by the evaluators. The methods were useful in identifying usability problems, and easy to employ using standard equipment and software thus a relatively low cost approach to usability testing.