Introduction of formal model-based practices into the development process of a product in a company implicates changes in the verification and validation activities. A testing process that focuses only on code is not comprehensive in a framework where the building blocks of development are models, and industry is currently heading toward more effective strategies to cope with this new reality. This paper reports the experience of a railway signalling manufacturer in changing its unit level verification process from code-based testing to a two-step approach comprising model-based testing and abstract interpretation. Empirical results on different projects, on which the overall development process was progressively tuned, show that the change paid back in terms of verification cost reduction (about 70%), bug detection, and correction capability.