defined and also a corresponding data structure event package for the transmitted charge information the application server u201c rch u201d transmits notify messages to u201c sip a u201d and u201c sip c u201d the content of the notify message to u201c sip a u201d and the content of the notify message to u201c sip c u201d are defined by the application server u201c rch u201d to enable a suitable display of data to appear at the terminals u201c sip a u201d and u201c sip c u201d it is necessary for the content and the relevant data structure to be agreed with the manufacturer of the sip user terminals the application server u201c rch u201d receives from the sip based voice network via any call control interface e g sip from a sip call control server or u2014 for example u2014 inap from the pstn gateway information about u201c sip a u201d user identifier e g e 164 regs start time and date of the sip connection end time and date of the sip connection destination b of the sip connection e g e 164 number in the pstn the application server u201c rch u201d determines the call charges and also the further user u201c sip c u201d pertaining to the identification of the user u201c sip a u201d on the basis of administered data and generates the aforementioned standardized sip message notify in accordance with rfc 3265 to u201c sip a u201d and u201c sip c u201d according to still another embodiment of the invention the user registration function of the sip.