alarm communications

As communication technology improved and emergency services became more stretched, it was desirable to remove the gram units which relied upon making a 999 call.

Upgrading to new digital communicators (Digicom) was the way forward, these units called a secure alarm receiving centre (ARC) and sent a digital signal to a computer which identified the premises, the information was then called through to the police by operators in the ARC. 

Whilst all looked good in the planning phase, and many hundreds of grams had been pulled out and upgraded, there were issues that had not been given full consideration. 

Firstly, many clubs, pubs, factories etc. provided a payphone for public use and to save money connected the gram to the same telephone line, this is OK when dialling 999 as this is a free telephone number, however as soon as a Digicom was installed, it dialled the local ARC, the payphone telephone line blocked the call on connection until money was inserted, which of course the Digicom could not do.

Further issues arose within a few months of the roll out, many telephone areas were subject to dialling code changes, hence a customer with premises in one telephone std code area dialling an ARC in another would suddenly have an issue. 

The Digicom looked to be working, dialling correctly, playing the digital code over the line, and closing down reporting signalling success, however the ARC reported no signals? 

It later transcribed that when dialling to old STD code, the telecoms provider blocked the line and played a message i.e. “dialling codes have changed, please redial using 01924 Beep”, unfortunately the beep was the same frequency that the ARC communicator transmitted to the Digicom for a successful transmission.

In addition to these issues, intruders started to understand that telephone lines were being used to make a phone call to an ARC, this gave them ideas, starting with breaking in and taking the phone off the hook to engage the line, to calling the companies phone number before breaking in or simply cutting all the telephone lines to the premises. 

It would take another 20 years to resolve this issue with a new type of secure signalling that could send data to the ARC over a telephone line even if it was in use at the time, and monitor the line giving a fault condition at the ARC should the line fail.

In the background, direct line signalling systems (a rented pair of wires from the premises to the ARC) were being upgraded, the cost of such rented lines was so prohibitive that only very high risk clients used them, in excess of £1,000 per year providing the premises were in the same telephone STD code area as the ARC, this meant that companies had to own ARCs in every major town and city to provide this service.

The upgrades started with MV signalling, this utilised a tone over the line rather than 24VDC which had been relatively easy to defeat, however this quickly became just as insecure as the 24VDC systems as intruders could listen to the tone on the line and tune a small electronic circuit to the same frequency, then connect their own “MV” and disconnect the alarm. 

MF was the next iteration, this used two tones sent continuously which generated a harmonic tone, the ARC receivers were tuned to listen to the harmonic and react if its frequency changed, even very slightly. 

The final iteration of direct line systems allowed up to fifteen customers premises to arrive at the local exchange, then share a single line to the ARC, suddenly the local ARCs could be amalgamated into a few regional units, reducing running and staff costs dramatically. 

It always fascinated me when connecting new systems onto the combined connections, using an earpiece across the line you could hear the tones, a background continuous tone, “wow, wow, wow, wow” then a call tone from the ARC computer, “Peep” followed by replies from each customers premises “pip, pip, pip, pip etc.”, and after connecting the new transmitter, the number of replies increased by one pip, you knew it was working before talking to the ARC.

A few interesting tales came out of this signalling solution; -

One customer living in a beautiful house in North Leeds, after numerous “line fault” call outs at all times of the day and night, asked me what could be done to stop the nuisance, I discussed how that these “phantom” line failures were down to the telecommunications provider from whom  he rented the necessary pair (of wires to the ARC) and that they may drop out due to bad connections, testing or a host of other reasons. 

I advised that it was not possible to eliminate these issues, however the customer resolved the matter himself, he ordered another pair, paid for a second signalling board and simply advised the ARC, “don’t call me unless they both go into line fault”, this resolved the issue, but doubled the rental cost to in excess of £2000 per year just for the line rental, considering that was more than I was earning per year, it seems this customer valued his wasted time highly.

Another premises, a large warehouse storing valuable fur coats etc. utilised direct line signalling and had vibration sensors on the walls to detect intruders. The system was so secure, yet the goods were so valuable that a new strategy was developed, the intruders hammered on the wall three to five times every night causing the alarm to activate and the police to be called. 

After a few weeks, the police stopped coming, so that night they knocked down the wall and took several lorries loads of goods worth an estimated 1 million pounds.

Customers such as banks with cash on the premises would pay for an extra level of security, open/close monitoring, in a nutshell, customers could set up time windows when they would open and close the premises, should they be late closing or the premises send an open signal at the wrong time, the police would be called to investigate, this helped to defeat intruders who held up keyholders and forced them to open their premises. 

All the direct line systems reported the times of opening and closing, however, unless open close monitoring service was set up and paid for, the ARC took no action other than to record the times. 

This service was designed to prevent high risk sites being opened or closed at times outside normal agreed working hours, which could indicate a robbery being committed, either by a corrupt keyholder or coercion of keyholders by criminals.

On more than one occasion, this little-known recording has caught out business owners committing arson for insurance fraud. 

Under suspicious circumstances, the police would be provided with the times the premises were opened or closed, they were then able to discuss the matter with the owner.

They were shocked to receive a visit from the Police asking,  so we have established you’re the only person with keys, the fire started at 2:00AM yet we can see that the alarm was opened at 1:30AM and closed again at 2:03AM, just how do you explain this?