The decisions of the European Commission oblige each member state to make every effort towards the availability of an external STM for their legacy ATP system by 31st December 2007. The Finnish, Norwegian and Swedish Rail Administrations have since 2003 developed a Specific Transmission Module (STM) product for Nordic markets with the Swedish supplier Ansaldo STS. The development of an STM is part of the chosen ERTMS migration strategy, which stresses the migration of the rolling stock equipment as the primary migration path. The development project started as an STM European mode, but due to insufficient UNISIG specifications the project has in 2007 been transformed into the STM Natio-nal mode. An STM using the National mode (STM-N) performs and is responsible for the train supervision. Project work continues intensively and the tests for the Swedish-Norwegian STM1 product can start in autumn 2008 and for the Finnish STM2N product in spring 2009.