Secure calls – voice encryption

Do you think your calls over GSM networks are safe?

Koolspan logoThat no one listens to your confidential customer calls? Recently the A5/1 code use for GSM call encryption in Europe was hacked within 3 months of being introduced. As a result there is a so-called “rainbow table” sized 2TB which can be used by almost anyone to decode phonecalls. The table is now available on public internet.

Secure your calls with Koolspan TrustVoice

Now you can prevent illegal listening with Koolspan TrustVoice

  • KoolSpan’s TrustChip – a fully hardened, self-contained security engine
  • Meets the FIPS 140-2 Level 1 – American standard for computer security
  • Intuitive interface, call (TrustVoice) and SMS encryption (TrustText)
  • Encryption keys are stored on an individual microSD card with TrustChip
  • Compatible with BlackBerry and Android
  • Central control, option to remotely disable the chip in case of loss or theft

The solution is a combination of the TrustChip, a simple application in the mobile device and a relay server.

End-user interface

Simply look up your contact in the address book and select “Place Secure Call”. The smartphone will connect to the server, verify authentication and connect the secure call. The voice is converted into a .amr file and encrypted with a 256-bit key. It is then sent as data and decoded by the receiving device.


How does it work technically??

A signal is sent to the destination device (using SMS or BlackBerry PIN message) to request an encrypted call. Both devices then connect to the relay server, authenticate and create a secured connection. The conversation is protected via an end-to-end encryption – voice is converted into data, encrypted and can only be decrypted on the other phone.
This solution can be supported and controlled remotely with TrustCenter Suite.
The device is only connected to the server for the duration of the call, which helps to save the battery.


The solution can be hosted either at our data center or on the customer’s infrastructure.

For more information or to request initial consultation, please contact System4u.

© 2019 System4u, a.s.
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