Select Committee on Northern Ireland Affairs Minutes of Evidence


Memorandum submitted by British Telecommunications plc


  This Memorandum addresses the questions posed by the Northern Ireland Affairs Committee in respect of BT's response to the problems experienced by NIE between Christmas and New Year 1998.

NIE HELP LINE 0345 643 643

  Calls to the 0345 643 643 Help Line are routed in the first instance to NIE's own call handling agents, based at a number of locations across Northern Ireland. When all available NIE agents are busy, any remaining calls overflow to the Message Link service which provides pre-recorded information for callers. Under normal circumstances, Message Link can be updated remotely at will by NIE.

  A day by day breakdown of the number of calls made to NIE 0345 643 643 Help Line during the period 26 December to 1 January 1999 is given at Annex A. The figures show that the Boxing Day storm stimulated an unprecedented number of calls to the NIE Help Line, which amounted in total to 651,684 calls in the period up to 1 January 1999.


  Problems were experienced by NIE with updating the pre-recorded Message Link announcement during the evening of 26 and the morning of 27 December. A problem was reported to BT at 1835 hours on 26 December, though BT was, at that time, unable to identify a specific fault. BT did recognise and acknowledge that the NIE were experiencing problems in updating the message remotely.

  BT can now confirm that there was no fault on the Message Link service at any time, and, following the incident, further investigation has identified the cause of this problem. Access to amend the recorded message on Message Link takes place over the same lines as customer calls to Message Link. As a result of the congestion caused by exceptionally high volumes of calls overflowing to the Message Link service, NIE personnel were unable to get through themselves to make the change to their announcement. The congestion continued until the Sunday afternoon (28 December) when the call volumes to the Message Link service started to reduce and NIE were able to get through and change the announcement. The Message Link service continued to work effectively during this period. As a result of the high number of calls and complaints that NIE received, NIE asked BTNI, on the morning of 28 December, to mobilise some BT agents to take calls from their customers. During the period from 28 to 31 December, BTNI call handlers dealt with over 12,000 calls on behalf of NIE.

  Reference has also been made to the fact that some of BT's local exchanges became overloaded due to the unprecedented number of calls to the Help Line number in such a short timescale. BT can confirm that some congestion was experienced at a number of our small rural exchanges on both 26 and 27 December due to the high volume of call attempts being made to the NIE Help Line. The telephone exchange design and route capacity are dimensioned to cater for the normal daily busy hour traffic levels. This exceptional surge of traffic in addition to the normal calls resulted in a small number of our local exchanges experiencing congestion at peak times. The most serious congestion was experienced at Lisnaskea, Florencecourt and Claudy exchanges and resulted in our customers receiving "equipment engaged tone" as they attempted to dial out.

  It would simply not be feasible to design the switch or provide the route capacity to cater for such unprecedented and infrequent surges of traffic. There would also be little advantage in advancing the calls to the destination number if there were insufficient lines or agents available to answer them.


  The Report comments "that BT had at times to restrict the number of calls to NIE directly to maintain the integrity of its network" and the reasons for this should be clearly understood.

  BT's network successfully delivered a total of 550,133 calls (see Annex A) to the IE Help Line 0345 643 643 on the 26 and 27 December. It was able to cope with this unprecedented volume of calls as it was a holiday weekend during which there was little other commercial traffic calling the 0345 range of numbers.

  On Monday 28 December there was a significant increase in the level of normal commercial telephone traffic from post-Christmas promotions, catalogue sales and retail activity, etc., which resulted in an overload on the national 0345 platform. When more calls are initiated to the various 0345 numbers than the companies employing them have the capacity to answer, BT's network can become congested and this may prevent other calls, including those to the emergency services, being able to get through. When it is necessary to prevent this, and thereby to protect the integrity of BT's network, national Call Gapping is introduced. This means that BT limits the number of calls that are forwarded to the dialled number at any one time. If this did not happen, major congestion, which may impact on the remainder of BT's network, is possible.

  Between 0913 hours and 1226 hours on Monday 28 December, BT found it necessary to introduce Call Gapping because of the serious level of route congestion that was being experienced on the national 0345 platform. As a result of Call Gapping, the number of calls allowed through to the NIE Help Line number was limited during this three hour period, but overall BT's network successfully delivered 651,684 calls to the NIE Help Line number.


  The Committee should also be aware of the problems that the extensive and prolonged power failures created for BT itself in Northern Ireland during the period in question.

  BT experienced a number of serious service difficulties as a direct result of the NIE faults and power surges induced data corruption on a number of our network control links. In total we experienced 52 short duration exchange isolations on 26 December which resulted in 19,000 of our customers experiencing a total loss of telephone service for a few minutes on each occasion.

  All telephone exchanges require continuity of power supply to remain operational. Following the Boxing Day storm, BT experienced the most extensive and prolonged power supply failures on record. However, to minimise any disruption of service to our customers, all BT's exchanges are equipped with standby electricity generators, installed as part of our planned network resilience. By design, these are only intended to cover short break interruptions to the power supply to sustain continuity of service to our customers. To illustrate how serious the situation was on 26 December, 80 of our telephone exchanges lost their power supply at some time during the day. Without our standby capacity, BT would have lost telephone service to over 150,000 customers. A number of our generators had to run continuously for three and four days before mains power was fully restored.

  During this time BT's service was at risk. It is clearly important that the significance of BT's services is recognised and a sufficiently high priority assigned in any restoration and recovery plans. Clearly these are issues which BT will discuss further with NIE to ensure that we are given appropriate priority in future recovery and restoration plans. Even so, it was reassuring to note how well BT's telephone network handled such an unprecedented volume of calls, despite the impact of such extensive and prolonged power supply failures.

  The telecommunications network infrastructure itself also suffered extensive physical damage as a direct result of the severity and duration of the Boxing Day storm. BT's fault volumes increased by 300 per cent in the week following the storm: 317 poles were brought down, 1,700 realigned, 3,540 overhead lead-ins to customers' premises had to be renewed and 210,917 metres of aerial cable replaced.


  As a direct result of this incident, BT has already held a joint Workshop with NIE to investigate and agree how we can work together to improve their call answering facilities. Proposals already being discussed include:

    —  developing additional contingency call answering back-up capacity which can assist NIE during periods of heavy demand;

    —  the introduction of Interactive Voice Recording (IVR) equipment into NIE's advanced services call plan to improve the effectiveness of the call answering agents and to reduce call handling times;

    —  review of the design of Message Link access facilities to provide priority access for message updates during periods of high call volumes; and

    —  recognition by NIE of the critical importance of BT's services and assignation of higher priority in future restoration and recovery plans.

  It was reassuring for BT to see how well our own network infrastructure stood up to the storm damage and major power failures. It was also reassuring to note how well our own fault reporting procedures and emergency restoration plans stood up to the impact of this storm.

BT Northern Ireland

March 1999

Daily Record of Call Volumes to NIE Help Line
CallsCumulative total Percentage
26 December304,909304,909 47
27 December245,224550,133 84
28 December49,893600,026 92
29 December31,926631,952 97
30 December 11,477643,429 98
31 December5,294648,723 99.5
1 January 2,961651,684 100

Faults Reports to 151
26 December1,7201,024
27 December4,991650
28 December5,0522,201
29 December5,3691,935
30 December5,1841,869
1 January3,2411,895
Fault report call volumes increased by a factor of 2.66 against normal fault levels.

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