Fintraffic ANS participates in the Iris Pre Commercial Flight period (PCF). During the PCF period, CPDLC service will be provided via Iris SATCOM connection to those aircraft that meet the requirements to participate in PCF. The Iris Service is provided by the European Satellite Services Provider (ESSP).
 

Further details can be found in the ESSP Iris Service Definition Document:
 

https://satcom-dls-support.essp-sas.eu/documents/iris-service-sdd
 

For all other aircraft, CPDLC service is provided in Helsinki FIR area in Enroute airspace as stated in AIP of Finland, section GEN 3.4.