Introduction: In hospitals, the discharge of patients needing home care or going to a care facility is planned interprofessionally, in particular via telephone calls between nurses and social workers. Context: During discharge planning, the collaboration between a nurse and a social worker is fraught with tension. When this planning is conducted over the phone and the nurse is a new graduate, the tension can be heightened. Method: Sociological study in an acute-care hospital in French-speaking Switzerland based on analyses of telephone conversations between new nursing graduates and social workers, in addition to observations, interviews and document-gathering. Results: Discharge planning is fraught with tension related to the timing of the planning and the care requested. The telephone calls are opportunities for new nurses to learn how to present cases, the procedures to follow for discharge planning, and the work logics of the individuals involved. Discussion: The study confirms the need to prepare new nurses to work with social workers on discharge planning and recommends offering training in this, both in nursing school and in the workplace. Conclusion: Research documenting real work practices provides the keys to perfecting them.