Crypto Voice over GSM

Functionality of Stealthphone Hard hardware encryption device in Crypto Voice Over GSM mode

A unique and unrivaled technology, designed by Mobile Trust Telecommunication.


Existing solutions in mobile phone security use Voice over IP technology to transmit encrypted voice, but the main drawback is the quality of voice or no connection at all if the Internet connection is bad.

Crypto Voice over GSM technology, developed by Mobile Trust Telecommunication, allows you to make encrypted calls without the access to the Internet.

Crypto Voice Over GSM mode allows the subscribers to use standard GSM channel for transmission of encrypted voice without any other additional equipment. Crypto Voice Over GSM technology is one of the components of Stealthphone information security solution for corporate customers and state organizations

One of the distinctive features of Crypto Voice Over GSM is the possibility to transmit voice with minimal distortion even with low signal.

Crypto Voice Over GSM is simple to use. Any Bluetooth-enabled device supports VoGSM. You do not need any additional software. Encryption is done with a separate device – Stealthphone Hard, a hardware encryption device that has to be used by all participants of a communication.

With the access to the Internet you can switch the Stealthphone Hard encryption device from Crypto Voice over GSM  mode to Crypto Voice over IP

Special features of Crypto Voice Over GSM

You mobile phone conversations can be intercepted by the mobile operator or criminals with the help of special technical equipment.

If you use only software solution to protect your conversations, criminals can exploit undocumented features of your mobile phone and capture audio signal directly from the microphone or use the remotely planted viruses for the same purpose.

That is why we have implemented Crypto Voice Over GSM solution in a stand-alone device that exchanges only encrypted data with the mobile phone. The user talks on the encryption device (that complies with TEMPEST standard), which serves as a headset. This secures you against the criminals who are trying to covertly extract data from your phone.

Any data sent via voice GSM channel is processed as digitized speech. GSM and 3G networks employ advanced methods of signal compression in order to use communication channels efficiently. The signal, encrypted by Stealthphone, is barely affected by voice compression algorithms, which results in a high degree of sound clarity

Download this PDF to learn more about strength of cryptographic transformations.

Operating Stealthphone Hard in Voice over GSM mode

Stealthphone Hard hardware encryption device is a standard wireless headset connected to a mobile phone via Bluetooth. In unprotected (clear) mode Stealthphone works as a standard headset. There are two ways to enable secure mode:

  1. Automatically;

  2. Manually, by pressing Encryption button during the conversation and enabling speech-like noise. To enter secure mode the encryption devices generate one-time (session) key. Generation usually takes a couple of seconds. Key generation interrupts the conversation, then it continues, but in encrypted mode.

It's important to note that long-term keys (previously generated and saved in Stealthphone encryption devices) are used to generate session keys. The administrator of Stealthphone network generates long-term pair bond keys required for authentication of the users. That means that no third party (including MTT employees) can decrypt your conversations.