The present invention relates to a method of and system for managing financial liability in a telecommunications network wherein a service requester (1) receives post paid services provided by a service provider (2) and wherein financial liability of said service requester for payment of said services is certified by a liability provider (3). At least one liability token data signal is received by said service provider via said telecommunications network (8), which at least one liability token data signal is issued e by said liability provider. Said liability token data signal comprises time dependent validity data for said liability token data signal and data regarding an amount for which said service requester is liable. The invention is also related to a liability server for use in a method and system according to the invention.