the present invention relates to a private telecommunications system comprising a number of switching arrangements and using an asymmetrical protocol supporting set up of virtual calls between two switching arrangements for transfer of information . means are provided for creating a call reference in the first switching arrangement when a first virtual call is to be set up from the first switching arrangement to a second switching arrangement , storing means being provided in said first and second switching arrangements for storing said call reference . said first virtual call is released while all internal connections and the end points related to it are kept , and a second virtual call is set up in the direction opposite to that of the first virtual call using said call reference such that symmetrical transfer of information is enabled between the two switching arrangements .