Formal requests were recently introduced for integration of ICT in secondary school mathematics. As the main issue, students must develop competence to decide when and how it is appropriate to use available ICT tools and to use them. These new requests put demands on those teachers who have not developed corresponding competencies themselves. Danish GeoGebra Institute (DGI) designs training sessions for teachers, with the aim to initiate or support professional development to meet such needs. The design of these sessions does not see mastering the software GeoGebra as an end but as a means for the teacher to reach his teaching goals. Although we see good reasons to choose GeoGebra, other software might serve the same purposes. The paper presents our model for the design of teacher training sessions aiming at ICT--integration. The model's design is centred on four "essentials", mapping out the influence of ICT for mathematics education. First try out of our model, in a recent project in a small school with ten teachers, is reported in the paper. (Contains 1 figure.)