Background: In Denmark, patients with Inflammatory Bowel Disease (IBD) and disease in remission are mainly seen on a regularly basis in outpatient clinics, by gastroenterologists. Replacing the regular visits with annual telephone calls performed by IBD nurses seems beneficial, both for the patients and for the outpatient clinic. The purpose of this study was to identify potential barriers and pitfalls in the planning and implementation phase of a nurse-led telephone service. Methods: Preparations prior to introducing the annual telephone calls were done in 2010. From January 2011 all eligible IBD patients were shifted from regularly visits to annual telephone calls performed by an IBD nurse. As the intervention contained of several sub-elements and the elements were subject to adjustment during implementation, the intervention was regarded as a Complex Intervention. All the elements in the study, during preparation and implementation were monitored and visualised in a PaT Plot. Continuous corrections in the intervention were done. The identified problems and their solutions were the basis of this research. Results: Consensus regarding the eligibility criteria of the IBD patients for the intervention was a challenge between the different groups of health professionals. Tools for consistent practice and documentation of the telephone line had to be developed and adjusted. Competences for the involved IBD nurses had to be described, systematised and undergo continuous development. Furthermore, consensus regarding the nurse-competences had to be established among the groups of health professionals. Daily scheduled supervision by a gastroenterologist is essential. A high information level needs to be maintained in order to secure continuous commitment among all the health professionals involved. Finally, IBD patients’ response to the intervention had to be taken into account, not only in the planning phase, but also during the intervention. Conclusion: Changing practice, from scheduled regularly visits in the outpatient clinic to annual telephone calls by IBD nurses, takes time. The nature of this kind of intervention is multifactorial and several elements will have to be corrected during the implementation period. Therefore, it is recommendable to regard the intervention as a Complex Intervention and treat it as such.