The Integrated Voice, Fax and Data Encryptor (STN-SEC_VDF)provides communications security for users in the modern government and business environments, through the use of contemporary encryption and digital transmission techniques. These techniques give maximum protection while at the same time being reliable and easy to use. The STN-SEC_VDF is a stand-alone encryption device, which is used in conjunction with a standard analog desktop telephone, computer system or fax. Integrated Voice, Fax and Data Encryptor can be configured to operate at relatively low speeds; it can be used to secure communications across limited-bandwidth satellite circuits, PSTN, EPABX, Extension, REX, ASCON, VSAT, and Radio Relay etc.

The Integrated Voice, Fax and Data Encryptor offers different levels of security which users can select according to their needs in different situations, ranging from interpersonal communications to secure military and government use. Encryption uses a 256-bit encryption algorithm, or the STN-SEC_VDF can be configured to use an alternative such as a proprietary or a customer-specified cryptographic algorithm.

The STN-SEC_VDF uses unique encryption keys to protect each conversation or fax transmission. New keys are created at the start of each communication, and the session is established using a secure environment protected by keys loaded by the customer. For normal use, the STN-SEC_VDF can be configured to generate its own key exchange keys from Customer and Group Codes entered by the user through the keypad. For more critical applications, it can operate using cryptographic "Net Keys" generated within the customer's independent key management system. These are loaded into the STN-SEC_VDF using a special-purpose Key fill device.