Telecommunications systems

A method of inhibiting call charging including detecting a permanent or transient fault using the method of any preceding claim and, if the time elapsed between an apparent call answer condition and a call clear condition occurs within a predetermined minimum period and subsequent testing determines that a call is probably ineffective, inhibiting call charging in respect of a corresponding billing CDR.

A network management system including control means arranged to receive from each of a plurality of telecommunication switches a respective log of call detail records (CDR's) each including at least the identity of a network exchange node and/or a network user termination to which a terminating call has been directed and in which following application of a signalling condition change and an apparent answer condition and the period between the answer condition and a call clear condition is less than a predetermined period, the network management system including means to establish in respect of each terminating network exchange node and/or each end user termination featuring in at least one CDR an accumulator, the system further including comparison means for determining for each CDR the presence of an accumulator established by a previous CDR including the same terminating network exchange node identity or network user termination identity and to increment the respective accumulator, each accumulator being periodically compared with a threshold to determine the presence of a potential fault at or between the terminating network exchange node and the network user termination.

A telecommunications switch including control means to determine for each terminating call thereon, return of an answer condition in response to an applied change of line signalling conditions, said control means also determining a call holding period between the answer condition and a call clear condition, said control means creating for each terminating call in which the call holding period is less than a pre-determined period a call detail record including at least the identity of the network user termination for transfer to a network management system.

A telecommunications network including a plurality of switch manager systems each polling a respective plurality of digital local exchanges (DLE) to receive call detail records relating to calls terminating at network user terminations and which have been determined within the respective DLE which serves said termination to have had a call clear condition occurring within a predetermined short period after a call answer condition which in itself occurred after application of a change in line signalling conditions applied at the network exchange node serving said termination;

• the network further including a network management system arranged periodically to poll each of the switch manager systems and to receive the (CDRs) for all of the DLE's, the network management system determining from the received call detail records the identity of each network user termination featuring in at least one CDR and thereby identifying network user terminations which are potentially faulty, the network management system further providing a prioritisation of network user terminations in dependence upon the number of times the termination features in CDR's within a pre-specified period of time.

A method of detecting permanent or transient network faults in which a call billing system transfers billing CDRs to a network management system, the network managements system comparing CDRs with each other to determine the occurrence of a multiplicity of short duration calls to a particular network user termination within a pre-determined period, control means of the network management system creating an action list in respect of each potentially faulty network user termination for transfer to a line testing system.

35 A method of identifying a potentially faulty network termination point as claimed in claim 34 including notifying the administration serving the faulty network termination point.