Emergency off network communications for Ukraine

Physics of Shadow and Light
2 min readFeb 25, 2022

Update: Reminder to be extra careful when clicking links. Ukraine’s ministry of defense says Ukrainian’s should turn off geolocation on their phones.

As one who grew up in the days of wired wall phones, HAM and CB radio I marvel at the capability of mobile phones. They’re pocket-sized with excellent range and sound quality and their battery can last for days. But those of us who understand how cellular technology works also see their Achilles heel. They depend on an infrastructure which can be fragile during times of war.

When hurricanes and other natural disasters wiped out communications networks, some people began using apps such as Zillow for emergency communications. Zillow may be more efficient at sharing bandwidth and can be used as a temporary ad-hoc emergency communications system. But like voice, data and SMS, it still relies on cellular network towers. If there is no cellular coverage, a Zillow-equipped phone is useless.

Fortunately cell phones there are true peer-to-peer communications apps for phones. These rely on a phone’s built-in blu-tooth or WiFi transmit and receive capability and are only useful for short range (typically 100 metres or less) communication. Some of these apps are able to use other devices to relay messages for longer distance communication. An ad-hoc “mesh” network

I’ve had the most experience with a prototype-quality app called Servel mesh for android. I’ve used it along with a portable Wifi repeater to provide about 100 metres of voice or chat communications. I’ve used it on android 4.0.3 and earlier and there was a version for the older Nokia Symbian operating system. Unfortunately servel mesh is no longer actively maintained.

The next best app I can find for the people of Ukraine to use if anything should knock out cellular service is an android app called Briar. It has been useful for protestors and journalists as it is able to communicate short-range peer to peer via blu-tooth and over the anonymized Tor network. It also avoids storing too much information on your device in order to protect you and your network if your phone is ever stolen or seized.

I’ll write more as I learn more but I hope this app is useful for anyone whose communication infrastructure is hacked or otherwise compromised.



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