Why some alarms equipment might not work post Digital Switchover All telephone lines will be provided with a new broadband router (or adaptor) with its own built-in telephone socket that will convert traditional phone calls to the digital network packets. In most instances, existing telephone equipment should, therefore, continue to work as normal. However, for older hard wired alarm and intruder alarm systems, there is an additional barrier. In the 1960’s, a simple method that used audible ‘tones’ was invented to allow us to signal to telephone exchanges who we wanted to make a telephone call to, so that computers at the exchange could automatically route our calls without us having to speak to an operator. Each of the numbers on the telephone keypad has a unique corresponding tone. Many hard wired alarm and intruder alarm systems have developed extremely complicated sequences of tones to send over information. When an old fashioned hard wired alarm system makes a phone call to an alarm receiving centre - tones denoting where the call came from and what the call is about are sent to the alarm receiving centre as a series of beeps at the start of the call. Alarm receiving centre software then decodes those tones, and uses the information to display on screen the matching customer record. A simple example is that if a telephone call from an alarm unit came from block 1, flat 36 - the alarm equipment might send through the tones that correspond to 001 036 so that information could automatically be displayed on the system at the alarm receiving centre. The risk of tone distortion after the Digital Switchover Just like someone’s voice would be on a call, any tones are also converted into network packets and sent using internet technology. The network packets are reassembled at their destination to play the tone as it was intended. However, if any of those packets are delayed, or for some reason do not arrive at their destination because of a technical fault, even by only fractions of a second - the tone can sound different at the other end. This is particularly the case for tones that are played extremely quickly and in very short bursts, which is how some alarm systems communicate. In those circumstances, it is therefore possible that the computers listening for those tones might not be able to recognise all of them. This creates a risk that an alarm receiving centre receiving a telephone call from an alarm system, might not sometimes be able to recognise the tones played to it, and therefore might not be able to automatically lookup all the right information about the caller. These delays in packets getting to their destination do not generally cause a problem in normal conversations, humans don’t generally even hear these changes in tones. In fact, calls made using packets can often sound better and even clearer to humans. This means that some hard wired intercom systems, alarm systems, answering machines, and intruder alarms that are connected to telephone lines may not work, or work reliably 100% of the time, unless they are replaced entirely with something different or changed. 6
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