sapi during e g start up of a processor in a node or during the making of the 1 st sndcp layer on a processor in a node which processor is handling the sndcp layers the common compression entity for unacknowledged mode ref fig5 traffic can be created installed this can e g be done by means of a function written in the u201c c u201d language and defined like this u201c extern int sndcp_v42bis_install_common_comp_entity_for_unack void u201d when this function is executed in the processor memory needed for the common compression entity is allocated and standard v 42bis variables which are to be used by the common compression entity are ready for initialisation typically in known systems and in contrast to the method of the invention the creation of a compression entity is done much later during the handling of xid commands and responses the common compression entity which is created and installed on the node processor as described by way of example above typically provides the normal functions for handling the standard messages like c init c data etc these functions can also e g be defined to be accessible as globally available functions u201c extern u201d such that all sndcp layers associated with the processor of the node i e handled by the node processor can access the common functions that handle the reception of c init c data and flush commands in the common compression entity accordingly the function of the common compression entity can be accessed from all sndcp layers by such an u201c extern.