The present document specifies the stage 3 description of the Supplementary Service Talking Party Identification (SS-TPI) for the Terrestrial Trunked Radio (TETRA). The SS-TPI supplementary service enables the party/parties participating in a call to receive the identification of the talking/sending party. The SS-TPI is activated against individual identity in individual call and against group identity in group calls. Man-Machine Interface (MMI) and charging principles are outside the scope of the present document. The supplementary service stage 3 description is preceded by the stage 1 and the stage 2 description of the service, according to the method des