A Simple and Secure Alarm Signalling Solution

Developing since 2002, the Terrier system links alarm systems to the monitoring centre without intermediaries. The system sits within the host’s network and its security policies.

We provide alarm signalling systems to independently-minded organisations. The system consists of (a) software applications running on customers’ servers and (b) alarm communicator devices called SPTs. The organisation’s alarm systems – Intruder, Fire and many other types – are each connected to an SPT to provide the link to the organisations’ alarm monitoring system.

Terrier SC supply the SPTs – designed and manufactured in the UK, they conform to current UK specifications with many useful features. Most devices have data SIMs sourced from an international supplier and managed by our support systems. All our products – server applications, SPTs and SIMs – are competitively priced ensuring our customers have reliably low cost of operation. Our technical support ensures the reliable operation of the system with both regular maintenance, emergency response and technical updates. We regularly update our systems to improve usability by listening to feedback.

System Overview

The monitoring centre normally has two Alarm Receiver applications running on separate servers with one operating as the Primary Receiver handling all SPT connections. Both the Primary and the Standby Receiver are connected to the Alarm Monitoring system to pass on messages coming from the SPTs. The Receiver also monitors the connection to each SPT and will report any loss.

The Config Server is location independent and all SPTs are programmed to find it Its purpose is to manage SPTs to the correct Receiver initially and in case of a network or server failure.

The SPT’s first task is to connect to a Receiver and then to pass alarm messages to it. The messages come from the connected alarm system and also from the SPT itself and allow the Receiver to fully monitor the status of the connected SPT. Should the SPT connection fail, the Receiver will pass a fault message to the Monitoring Centre.

Full details of the connected SPTs are available to the operators of the Alarm Monitoring Centre and there are tools to manage much of the SPTs functionality.

IP Alarm Communicators

Pictured is the Dual-Path SPT531 pcb

It is normally installed in the host alarm system control panel or else in a power supply unit

We stock large box PSUs suitable for Security Grade EN2 and EN3 applications.

The SPT531 was released in May 2021 to take the place of the SPT431 in the previous line-up. Our Single-path products are still the successful SPT4 variants and the full range is:

Dual-Path SPT531 with both LAN and wireless GPRS connectivity, multi-inputs, supplied with Freely Roaming SIM and will operate as Security Grades DP2, DP2+, DP3 or DP4 as appropriate to its use.

Single-Path Wireless Only SPT420 a simpler model having just 16 pin inputs and connecting via GPRS only with a Freely Roaming SIM. It is available with Security Grades SP3 or SP3+

Single-Path LAN Only SPT411 more like the dual-path product with multi-inputs. It connects over any wired network having an Ethernet interface. Used with Security Grade SP4.

IP Alarm Receiver

Pictured is the overview page from the User Interface of the IP Alarm Receiver. It shows the status and wireless signal strength of each SPT

Our customers’ systems are a lot tidier than the test environment shown here

The SPT Detail page, reached by clicking the little pencil, provides more information


We provide on-line support to our customers and to their alarm engineers

Our Support portal pictured opposite provides the tools for us to examine any issues and make recommendations if remedial action would be appropriate.

An example would be if wireless signal strength had reduced our support process will also examine SIM behaviour and check that data sessions are reliable and consistent.

Our support process will also examine SIM behaviour and check that data sessions are reliable and consistent

Over the last few years, customer feedback has shown that there are users who would appreciate having some of the support tools that we have developed. Pictured opposite is the SPT Tools page from the IP Alarm Receiver user interface where the customer can name the site, set the local IP Address etc.

About us

Terrier SC Ltd started developing early IP alarm communicators when ADSL started to be available in the UK. It was becoming clear that the widespread adoption of Broadband would revolutionise communications and make Monitored Alarm Signalling much cheaper. At the same time, telecommunications companies were also improving the data capabilities of mobile phones and laying the foundations for the widespread use of mobile data that we have today.

With a background in alarm communications, Tony Tibbles had worked for several large security companies specialising in alarm signalling and their monitoring centres. He realised that the previous monopolies in telecommunications would give way and smaller companies could successfully develop new products and services.

Terrier SC Ltd founded in 2002 is based in Kent and is a small company with a network of trusted contractors and suppliers.


Get In Touch!


Terrier SC Ltd, 184 Bullen Lane, East Peckham, TONBRIDGE, Kent TN12 5LU

Phone Number

+44 (0)1622 871118



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