gprs tunneling protocol at step 100 it is detected that no acknowledgement or positive response has been received within a predetermined acknowledgement period for a given charging data record set that was transmitted from the charging data record generation unit to a first charging data record collection unit of its associated charging data record collection units in an embodiment the acknowledgement that should be received within the predetermined acknowledgement period may include a u201c data record transfer response u201d message of the gtp u2032 protocol or an u201c echo response u201d message of the gtp u2032 protocol in response at step 101 it is checked whether processing of any charging data record set marked as a potential duplicate is currently pending with any associated charging data record collection unit if it is determined at step 101 that processing of at least one charging data record set marked as a potential duplicate is indeed pending then the method proceeds to step 102 on the other hand if it is determined at step 101 that processing of no charging data record set marked as a potential duplicate is pending then the method proceeds directly to step 105 therefore assuming that processing of at least one charging data record set marked as a potential duplicate was found pending at step 101 the method has now proceeded to step 102 at step 102 the pending processing of the at least one charging data record set marked as a potential duplicate is monitored.