The present document specifies the stage three of the Short Message Service (SMS) for the pan-European Integrated Services Digital Network (ISDN) as provided by the European public telecommunications operators by means of the Signalling System N0.7 Transaction Capabilities (TC) application protocol. The stage three identifies the protocol procedures and switching functions needed to support a telecommunication service (see ITU-T Recommendation I. 130 [6]). The SMS is provided independently of a call. Charging principles are outside the scope of the present document. Testing and maintenance requirements are outside the scope of the present document. The SMS enables the originating SMS user to send Short Messages (SMs) to the receiving SMS user via a Short Message Service Centre (SM-SC)@ belonging to the network of the SMS originating user or separated from the network of the SMS originating user. NOTE: The SMS is typically used between a Short Message service provider and a user of the Short Message service provided. The SM-SC can be connected to the network by SS#7 or behind a NE-SC with DSS1 or other protocols.