What the tests have shown
The test days are organised together with the Ministry of the Interior, the Rescue Board, the Consumer Protection and Technical Regulatory Authority, RIKS, Levira and TalTech. Testers received the alert on a test phone and filled in a feedback survey right after.
Test days
Tallinn, Pärnu, Rakvere, At sea
All alerts reached the devices, even at the edge of coverage. One important technical finding: when a phone moves from one transmitter’s coverage to another (Pärnu → Koeru), the same alert is shown again with sound. The cause and the fix are explained below.
Tallinn: Pirita, Kristiine, city centre
All alerts reached the devices. Indoor conditions and reflections between tall buildings were tested. A duplicate alert also occurred between the TV Tower and Kristiina transmitters, confirming the finding from the first test day.
Pärnu: three realistic emergency scenarios
Real emergency wording was used for the first time. All three alerts reached the devices with priority HIGH. In all three cases the device was inside the calculated danger area: 251–471 m from the centre and 234–552 m from the edge.
Indoor reception in 13 shopping centres
The signal was measurable in most large shopping centres in and around Tallinn. It was most stable in Kristiine Centre, Lasnamäe Centrum and Nautica Centre. In Viru Centre and Solaris the signal was intermittent. Results per centre are shown below.
Drive tests across Estonia
Two years of drive-test data were used to calibrate a coverage model that shows how much of Estonia a 20-site network would cover. The model also uses the points where no signal was detected, so the prediction errs on the cautious side. See coverage →
Pocket Siren Forum: closing event
The pilot’s technical results and tester feedback are presented to partners and other interested parties. A new version of the Pocket Siren app is shown that sends event updates (e.g. a storm going from orange to red) without triggering a new alarm.
How the alert landed
Share of respondents who agreed or strongly agreed (n = 72)
What makes people act
readiness to act = risk perception + message clarity + noticeability
A stronger, clearer signal (sound and vibration) meant greater readiness to act immediately. The average clarity rating of the alert was 4.2 out of 5.
- Forest fire: the highest perceived threat and the strongest urge to act.
- Missing child: the strongest emotional reaction and good understanding of the text.
- Flood: a weaker immediate reaction. Testers wanted clearer instructions on what to do.
Testers also wanted more explanation of how the system works and what to do when an alert arrives. That is why this site includes both technical and practical information.
The right alert in the right place
| Scenario | Danger area radius | Distance from centre | Result |
|---|---|---|---|
| Missing child | 484 m | 251 m | Inside |
| Flood | 828 m | 471 m | Inside |
| Forest fire | 813 m | 260 m | Inside |
The phone waits up to 5 seconds to determine its location and shows the alert if the device is inside the danger area. Next, we need to test how phones behave with a weak GPS signal, indoors and at the edge of the danger area.
Signal in shopping centres
Share of valid Pocket Siren measurement points per centre, with median RSRP. Measured with one phone along a typical visitor’s route through each centre.
Why the same alert arrived twice
On the first and second test days the same alert was shown again when the phone moved from one transmitter’s area to another (Pärnu → Koeru, TV Tower → Kristiina). The alert’s serial number was the same both times.
The geographical scope of the test alerts was set to a single cell (cell wide). Under 3GPP TS 23.041 a phone treats such an alert received in another cell as a new alert, even with the same serial number. The duplicate was therefore standard behaviour.
Set the geographical scope of alerts to the whole 5G Broadcast network (PLMN wide, PLMN 901-56). The phone then recognises the same alert as a repeat in another transmitter’s area too. When the content changes, the update number is increased and the phone shows the update.
The setting must be verified before deployment in a drive test where the phone moves from one transmitter’s area to another.