the aim of the invention is to address short messages in a fixed network , both to fixed - network terminals that are operated as standalone units in the fixed network or to terminals that are operated in parallel in said fixed network and to extensions of cord - connected or cordless fixed - network terminals that are configured as private branch exchanges and operated either as standalone units or in parallel in the fixed network . to achieve this , several numeric identifiers are assigned to each fixed - network terminal in order to address the short messages , in such a way that for a fixed network terminal that is configured as a private branch exchange , the numeric identifiers can be arbitrarily distributed among the extensions .