TAS has warned SingTel for the two recent exchange breakdown incidents. This follows a review of the full investigation reports submitted by SingTel on the switches' fault at Orchard Exchange and the software fault at ...
Singapore, 11 August 1997 | For Immediate Release
TAS has warned SingTel for the two recent exchange breakdown incidents. This follows a review of the full investigation reports submitted by SingTel on the switches' fault at Orchard Exchange and the software fault at Hougang Exchange.
For the Orchard Exchange incident which led to the intermittent disruption of telephone services in the Orchard area for several weeks from March to May 1997, SingTel's findings indicate that the outages were due to electro-magnetic interference in the environment around the Exchange which affected the switches' internal power supply. Modern telecommunication systems are very complex and there may be situations where service disruption occurs through no fault nor negligence of the operators. TAS is satisfied that the Orchard Exchange disruptions were not due to SingTel's negligence, and that SingTel has done its best to rectify the problem and to minimise the impact of the service disruption. SingTel has put in place additional preventive measures to further strengthen the resiliency of the switches, which should prevent recurrence of similar incidents.
In the case of the incident on 5 July 1997, a software fault triggered the interconnect switch in Hougang Exchange to fail. This switch interconnects the various cellular and paging operators together, as well as to the telephone network to enable interoperability. In order to restore this interconnect switch, SingTel had to restrict the volume and flow of calls passing through the switch and to reopen the switch to traffic progressively. This manifested as congestion to calls flowing through the interconnect switch, which thus affected calls made between mobile phones and fixed lines; mobile phones on different operators' networks; and all four paging networks. The software fault was fixed that evening on 5 July 1997, and paging and mobile services on all networks were normalised by 9.30 pm.
While TAS takes a very serious view of the two incidents, TAS will not impose a fine on SingTel since both incidents were not due to SingTel's negligence, and immediate action was taken by SingTel to rectify the faults. TAS has, however, issued a written warning to SingTel to be more vigilant, and to ensure that such incidents will not recur.
To prevent future occurrences of such incidents, TAS has directed all operators to re-examine and improve the resiliency of their networks. At the same time, operators are to devise adequate emergency and contingency communication plans to minimise inconvenience to subscribers, and to keep them informed during any major service disruptions.