One transmitter, every phone at once
Regular mobile networks send data to each phone separately (unicast). 5G Broadcast sends the same content one way to every device in the coverage area (one-to-many), just like digital television. Network load does not depend on how many people receive the alert.
From decision to phone screen
Rescue Board / Defence Forces
Decide to issue an alert and set the danger area, level and text.
EE-ALARM
The national public warning system creates a CAP message (Common Alerting Protocol).
NAKOLOS core
Receives the CAP message automatically and converts it into a 5G Broadcast alert (ETSI TS 103 720).
Levira masts
TRedess transmitters broadcast the signal in band n71 (E40/E41, 622–638 MHz).
Phone
Shows the warning with sound, vibration and text, and checks whether the device is inside the danger area.
On the test days, RIKS prepared the CAP messages in EE-ALARM and triggered them automatically. Levira monitored the transmission in the NAKOLOS system. The whole chain CAP → core → 5G Broadcast → phone worked without manual intervention.
Pocket Siren and other channels
| Location-based SMS | Cell Broadcast | Galileo satellite | 5G Broadcast (Pocket Siren) | |
|---|---|---|---|---|
| Network | Mobile network | Mobile network | Satellite | Broadcast masts |
| Depends on mobile network | Yes | Yes | No | No |
| Free text | Yes | Yes | No, codes only | Yes (up to 1,350 / 600 characters) |
| Alarm sound in silent mode | No | Yes | Device-dependent | Yes (highest level) |
| Images, maps, video | No | No | No | Yes |
| TV and radio on the phone | No | No | No | Yes |
| Phone support today | All | Most | No standard yet | Limited (see FAQ) |
Not every threat is equally serious
Pocket Siren uses the international EU-Alert / CMAS levels (ETSI TS 102 900). Tests confirmed that the highest level (national alert, 4370) goes off on every tested device regardless of sound settings. Lower levels follow the phone’s sound profile.
Levels 4371–4374 and the monthly test (4380) were used on the test days. In Pärnu all three scenarios were displayed with priority HIGH.
| EU-Alert | Meaning | Can be turned off? |
|---|---|---|
| Level 1 | National alert (Presidential) | No |
| Level 2 | Extreme threat to life and property | Yes |
| Level 3 | Severe threat | Yes |
| Level 4 | Public safety alert | Yes |
| EU-Amber | Missing child | Must be turned on |
| EU-Info | Advice (e.g. shelter, boil water) | Yes |
| Test / Exercise | Monthly test and exercises | Yes |
What one alert can hold
