BT's 21CN and Your Alarm Monitoring

If you have a monitored alarm system over the British Telecom landline, then you need to understand the consequences of sending signals over the new 21CN network. 21CN is an analog as an existing BT landline, it is digital, and uses Internet Protocol (IP) as its base protocol. On top of that, uses Session Initiation Protocol (SIP), which is the same protocol used by most Voice over IP network providers. It stands to reason that the 21CN network will suffer many of the same problems as the alarm systems have suffered for many years trying to send a signal through a network of 3rd party VoIP providers.

Unfortunately, most alarm companies are holding back to find out how their customers systems will be affected by 21CN. As explained in its BT 21CN trials document, not just a problem with its new network. Pre-select the local loop means that an increasing number of core network from other Telco's that are used to transmit alarm signals to VoIP (Voice over Internet Protocol) - often without the knowledge of alarm installations or users.

History has proven that the alarm panel modem and digital communicators are able to reliably transmit their signals over VoIP networks. 21CN may allow consistent results early, but will begin to suffer more as time passes and the increasing number of users to put the network under load. As a large number of customers you already have an Internet connection available, it makes sense to solve problems now rather than wait for the costly failures in communication.

One problem is that BT will not recognize the fact that they are likely to be many issues in the area of ​​alarm monitoring, however, other 21CN documents seem to contradict that view, which led to much confusion uindustrija security alarm.

In 2007, BT has told us that there will be problems with alarms signaling through 21CN. In 2008 we said "The system will be 'groomed' the trial 21CN Cardiff as a result of work done by the British Security Industry Association ."

In April 2009, BSIA announced test BT 21CN plana.Test plan was put together after nearly two years of development BSIA and its members, including extensive testing of the 21st Century network facilities at BT Adastral Park and Swansea.Glavni causes for concern are:

Echo cancellation is always used except for high-speed fax modem, or have been detected

audio discontinuity path will appear when the jitter buffer length change, either during a voice call or when the modems or faxes are detected.

can increase the round trip delay

test plan goes to state "Note: All results of the tests does not guarantee that the CPE (customer premises equipment) will be working on BT's 21CN network ".

So, with information as it is with BT and the alarm company with their head in the sand, you would be well advised to do your own research and look for the alarm companies and monitoring centers that question a little more seriously.