Roaming SIM
May connect to more than one supported mobile network. It can improve resilience but does not guarantee coverage everywhere.
Lone Worker Safety Centre
Connectivity and resilience guide
Connectivity claims need careful reading. A roaming SIM, eSIM, Wi-Fi, low-signal mode or satellite option may add value, but each has limits that must be tested against real work.
Comparison points
What each connectivity term can and cannot mean
Do not treat connectivity language as a guarantee. Ask what happens when signal is weak, absent or interrupted during a live risk event.
eSIM
May improve network flexibility where phone compatibility, app configuration, supplier service, subscription and network agreements support it.
Wi-Fi
Can support app or device connectivity in buildings, but employers must check permissions, reliability and what happens when the worker leaves Wi-Fi coverage.
Low-signal mode
Must be defined by the supplier. It may mean SMS fallback, delayed upload or a restricted operating mode, depending on the service.
Satellite
May require separate hardware and subscription. It may be SOS-only and may not provide every normal app, audio or ARC function.
Indoor location
May use Wi-Fi, Bluetooth beacons or other location aids. Employers should test accuracy in real buildings before relying on it.
Testing standard
Test the system where people actually work
Coverage maps and supplier descriptions are not enough. Managers should test homes, estates, clinics, rural sites, basements, plant rooms, car parks and travel routes that staff actually use.
- Record known poor-signal locations.
- Check whether alarms, check-ins and location updates still work.
- Confirm whether satellite changes the normal response model.
- Review whether higher-risk work needs a different device.
Field test protocol
Test connectivity as an end-to-end safety function
A signal icon does not confirm that an alert, audio stream, location update or cancellation will reach the intended responder. Test the complete route with the supplier or internal monitoring team using an agreed test mode. Include representative devices, networks, carrying positions, buildings, vehicles, weather conditions and work periods.
- Prepare the test
- Map known weak areas, obtain staff experience, confirm test contacts and define what success means for alert receipt, audio, location and response time.
- Exercise normal and degraded conditions
- Test indoors, outdoors, in vehicles and at coverage boundaries. Check what the user and responder see when data is delayed, the call drops, GPS is uncertain or the device changes network.
- Record a usable result
- Record location, time, device, network route, function tested, responder outcome, limitations and the agreed control. A general statement that coverage was “good” is not sufficient.
- Retest after change
- Repeat affected tests after network, application, firmware, handset, building, supplier or work-pattern changes and after any incident where communication did not behave as expected.
Fallback planning
Decide what happens before communication is lost
The fallback must match the risk. For some tasks a timed check and known route may be proportionate. Higher-risk or remote work may require satellite capability, paired working, a standby responder or a decision not to proceed.
Set the communication boundary
Confirm the last reliable contact point, task duration, expected route, missed-contact time and action if the worker does not reappear or reconnect.
Give staff authority to change the plan
Workers should know when to leave the area, return to coverage, use another system, request support or stop the task.
Investigate the control, not only the device
Review coverage, configuration, user action, monitoring receipt, location data, escalation timing and whether the original work plan remained suitable.
Evidence and limits
No connectivity option guarantees universal coverage
Roaming, Wi-Fi, eSIM and satellite descriptions depend on the product, network agreements, hardware, subscription and physical environment. Verify the supplier's written scope and the employer's fallback. Do not present a field test as proof that future service will always be available.
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