CallSec OS
A phone that runs CallSec —
and only what you allow.
CallSec OS is our hardened operating system. The phone is locked to our signing key, takes updates only from CallSec and talks only to the servers it needs.
Hardened from the first second
The phone belongs to your organisation
Verified boot with our key
Before handover the bootloader is locked again with our own key. From then on the phone starts only an operating system that we signed.
Updates only from CallSec
Signed system updates arrive over the air from our servers, over a connection that only phones of the fleet can open.
USB data off
The phone starts in charge-only mode. USB data and debugging can be switched on only remotely, by CallSec, with a signed command.
Panic PIN wipes the phone
Entered instead of the normal PIN, a panic PIN erases the whole phone.
Talks only to CallSec
An allow-list on the phone lets it reach only CallSec servers (and, while an eSIM is being installed, the carrier). The phone does not connect to Google — not for push notifications; services the hardware needs are relayed through CallSec.
Hidden destinations
The phone's connections to CallSec servers use Encrypted Client Hello and post-quantum key exchange, so the network sees less about where the phone connects.
Memory tagging
We choose phones with hardware memory tagging, which helps stop whole classes of memory attacks.
Locked-down radios
No 2G, no WEP, no automatic joining of open Wi-Fi networks, NFC off. eSIM is supported.
Managed remotely
Enrolled to callsec.si or to your own CallSec server; CallSec service commands reach the phone without a cable.
Hardware
Phones we choose for you
We install CallSec OS on new phones selected for their hardware security — memory tagging and a bootloader that can be locked again with our own key — and hand them over ready to use. The phone is billed at its cost; CallSec itself is licensed per device.
Equip your team with CallSec phones
Tell us how many people need a phone and whether you use callsec.si or your own server.