Digicom Alarm Signalling Problems

August 2012

A number of UK alarm receiving centres have recently experienced signalling failures which appear to have been caused by changes to the telecoms network.

The roll out of BT21CN/New Generation Networks across the telecoms network has been an ongoing cause for concern for alarm signalling for some time. A range of alarm panels and receivers were tested, in an initiative between the BSIA and BT, to determine whether ‘round trip delays’ could cause a signal to fail and the panel to retry continuously. One effect of this would be much larger phone bills for those subscribers affected. The other potentially more serious consequence could be that a fire or intruder alarm signal was lost.

However, the culprit this time, although still related to the network migration, may be that alarm messages are being corrupted at times of peak signalling as a result of data compression. No communication provider has made an official statement as yet - only that the issue is being investigated and a resolution being sought.  

Whatever short term fix is put into place this time, there is a longer term concern that this is going to be an ongoing problem and for a number of reasons.  Firstly, as the network migration to IP and consequent "round trip delays" gathers pace, more digicoms are likely to fail.  Secondly, data compression will be a continuing issue with network bandwidth limitations causing signalling corruption.  Equally concerning is that network changes are made by the providers with little or no advance warning.  The first the alarm receiving centre knows there is a problem is when they start receiving corrupt data.   

Installers, end users and alarm receiving centres are going to have to consider whether the PSTN network provides an adequate method for alarm signalling.  Increasingly, they will come to the conclusion that it isn't, particularly given the availability of cost effective and more secure alternative such as BoldNet IP.

Last updated 10th August 2012 

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