Critical Connectivity FAQs: IoT SIMs, rSIM, Routers, VoiceLink and Sector Solutions

Critical systems depend on connectivity that is secure, resilient and easy to manage. At CSL, we support organisations operating in environments where downtime, compliance risk and operational disruption can have serious consequences, from alarm signalling and healthcare monitoring to EV charging, smart metering, fleet telematics and retail payment systems.

This FAQ answers common questions about Critical Connectivity®, CSL’s sector expertise, and the products that help organisations keep connected devices and services operating reliably.

CSL provides secure, resilient connectivity for critical IoT, alarm signalling, emergency voice, healthcare, utilities, transport, retail and distributed estates. Its portfolio includes IoT SIMs, rSIM®, IoT routers, VoiceLink, CSL Satellite, CSL Broadband and Alarm Signalling, supported by management platforms and specialist service teams.

Critical Connectivity® refers to secure, resilient connectivity for systems where loss of connectivity could affect safety, compliance, public services or business continuity. CSL focuses on high-risk, regulated and operationally important environments, including alarm systems, healthcare and telecare, infrastructure, utilities, transport, retail and other distributed estates.

We support sectors including Building & Security, Healthcare & Telecare, Critical Infrastructure, Public Sector and Emergency Services, Industrial Operations, Transport & Logistics, Utilities, Retail & Hospitality and wider commercial applications. Across these sectors, the common need is secure, resilient connectivity for devices, sites and services where standard consumer-grade or commodity IoT connections may not provide the right level of control, support or resilience.

Different sectors face different risks. A fire alarm, lift alarm, smart meter, EV charger, telecare device and point-of-sale terminal all have different uptime, data, installation and compliance needs. Our sector-specific expertise helps organisations choose connectivity that fits the operational reality of their environment, rather than relying on a one-size-fits-all approach.

CSL’s solution portfolio includes:

Our IoT SIMs include access to a Connectivity Management Platform that gives visibility and control across a connected estate. Users can view SIM status, data usage, generate alerts and reports, manage SIMs, rSIMs and routers through one provider, and diagnose issues remotely. Customers also benefit from CSL’s account management and support services, built around life-, mission-, business- and geo-critical service operations.

rSIM® is CSL’s patented resilient SIM technology. Built on two independent multi-network roaming profiles, it monitors mobile network health and can autonomously switch to a backup profile during an outage, helping restore connectivity quickly for critical IoT applications. It is especially relevant where a single mobile network, or a multi-network service with a shared core dependency, could interrupt alarms, monitoring systems, healthcare services or other high-impact applications.

VoiceLink converts analogue PSTN voice lines to 4G VoLTE, helping legacy voice-first systems remain connected as PSTN networks are phased out. It is designed for use cases such as lift alarms, emergency lines, autodiallers, help points and PBX-related voice applications, with features including VoLTE voice quality, roaming SIM resilience and extended battery backup.

CSL IoT routers are designed for secure, reliable connectivity in locations where wired connectivity is unavailable, impractical or needs resilient backup. They can support applications such as smart buildings, industrial sites, telecare and housing schemes, retail point-of-sale, CCTV, ANPR and parking systems, digital signage and event surveillance.

For Building and Security, we focus on alarm systems, building control systems, surveillance systems and emergency voice communication. Our solutions support secure communication with Alarm Receiving Centres, remote management for building systems such as HVAC and access control, and resilient connectivity for CCTV and other monitoring applications.

We provide secure, reliable connectivity for healthcare and telecare applications such as home telecare, remote alarm monitoring, emergency response systems and healthcare worker support. Our solutions are designed to support resilient connectivity, secure connectivity infrastructure, PSTN-to-digital migration using IoT router solutions, and managed support for connected healthcare environments.

We provide secure, resilient connectivity for public sector estates, emergency services and local authority environments where service continuity, safety and operational resilience matter. This can include lift alarms, help points, emergency voice systems, telecare services, mobile command units, surveillance, ANPR, control room backup and connected field operations. Depending on the use case, CSL solutions can support PSTN-to-digital migration, primary or backup site connectivity, connected device management and resilient connectivity for critical or hard-to-reach locations.

In transport and logistics, CSL supports applications such as fleet management, vehicle telematics, asset tracking, route optimisation, EV charging, parking systems, surveillance and in-vehicle monitoring. Depending on the deployment, solutions may use multi-network connectivity, international roaming, LTE-M, 5G and eUICC capabilities to support resilient, scalable connectivity across mobile and distributed assets.

For utilities and critical infrastructure, CSL supports applications such as smart metering, renewable energy management, EV charging infrastructure, grid monitoring, telemetry and fault detection. These environments often depend on secure data flow, remote monitoring and resilient connectivity so operators can maintain visibility across distributed assets and respond quickly when issues occur.

Whether the challenge is maintaining alarm signalling, modernising legacy voice systems, connecting remote assets or managing thousands of IoT SIMs, we help organisations keep critical systems connected, monitored and resilient. For organisations operating in regulated, distributed or high-impact environments, the right connectivity strategy can reduce operational risk and make critical services easier to manage at scale.

Speak to us about the right critical connectivity approach for your sector, estate and application.