Select Committee on Northern Ireland Affairs Minutes of Evidence


Memorandum submitted by the Office of Telecommunications


  Oftel takes any failures in BT's network very seriously and reviews with BT the causes, lessons to be learned and implementation of improvements to prevent recurrence. I attach a memorandum on the operation of the BT network during the electricity supply difficulties over the Christmas/New Year period, which summarises the position to date.

  Our conclusion in this case is that work is required to ensure that the final overflow mechanism, the network message facility, is made more robust. We are awaiting BT's report on how this is to be achieved. Although outside our remit, to reduce demands on the network in the event of such a failure we are encouraging consideration of additional means of communication to be discussed in the dialogue between NIE and BT. For example, in the case of a similar failure, the use of a publicity campaign to inform the public of what the utility company knows and provide other relevant information, e.g., when supply will be restored in different areas, etc. If this information was available, some calls would become unnecessary and customers generally would be better informed.


  1. This memorandum addresses the issues raised by Clerk of the Committee in his letter of 5 March to the Director General concerning the problems experienced by Northern Ireland Electricity customers in the period 26 to 31 December 1998. The information presented is based on analysis of the NIE report into the incident and meeting with BT.


  2. The SI implementing the Revised Voice Telephony Directive contains provisions relating to security of network operations and maintenance of network integrity. Network operators are expected to take steps to maintain the integrity of their networks in the face of abnormal conditions. Measures to be applied in such circumstances could include the use of controls to regulate traffic flows to specific numbers experiencing abnormal levels of demand or controls to dampen more general network overload situations. The philosophy normally applied by network operators is to restrict traffic as close as possible to its originating point within the network and provide customers with an appropriate tone or announcement. Application of controls is a matter of judgment based on the circumstances of a particular incident and responses are often adapted as incidents develop. BT has detailed procedures for this aspect of its operations.


  3. The main points to emerge from OFTEL's review of the incident are as follows:

    —  there were very high levels of demand placed on the BT network in Northern Ireland in the early phases of the NIE incident;

    —  BT applied appropriate network traffic management controls on the NIE reporting number when traffic to that number became excessive and there was a risk that it could have adverse implications for other traffic within the BT network;

    —  BT assisted NIE by providing additional call handling resources from a BT call centre at periods during the incident;

    —  Non-answered calls at high demand periods were directed to a message facility. However, there were problems caused by an intermittent fault on that system which reduced the service capability below an acceptable standard. The time taken to correct the fault was unacceptable.


  4. The application of traffic management controls in circumstances such as those experienced on this occasion was a valid response for BT to ensure its network integrity. Such controls would be applied in response to any situation of this type at any time of the year to preserve network integrity.

  5. The intermittent failure of the Message Link Facility and the extended repair period are a matter of concern, OFTEL is reviewing these failures with BT to reduce the risk of a similar failure in NI or elsewhere, in future. OFTEL has also noted that BT has commenced a dialogue with NIE on the matter of restoration priorities for any future incidents and supports this initiative.

  6. There does not appear to be a case for substantial reinforcement of BT's network as a result of this incident. Inevitably whenever a situation of this type occurs, more is learnt about the way in which networks behave and how to improve operational processes and procedures.

  7. OFTEL work on this and other incidents has identified that BT reviews its operational procedures to ensure that improvements highlighted in incident reviews are, where practicable, carried through into practice.

  Oftel's investigation of this incident was self initiated following comments received from Utilities at a regular meeting between Government, Utilities and Operators. Other than through this route, Oftel has not received a formal complaint or any representations from consumers. This is one of a number of types of network incidents that Oftel investigates on an ad hoc basis.

18 March 1999

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