Polycom SoundStation 2W Application Note page 2

Security, rf co-existence and power management

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Polycom

designed the SoundStation2W™ to meet your needs for easy and reliable deployment.

This document outlines three key drivers for a worry free wireless solution.

Security on SoundStation2W:

SoundStation2W has proven and reliable security features in several areas: 1) 128-bit

authentication key for pairing the base station and console; 2) 64-bit voice encryption and DSS

frequency hopping on every voice call; 3) The AUX AUDIO feature is controlled from the console

rather than the base station (this feature allows external devices, such as a speaker, to be attached

to the SoundStation2W base station).

Pairing and Authentication

Every SoundStation2W has its base station and console pre-registered (paired) in the factory with a

unique 128-bit authentication key. When a system is installed the authentication key is verified,

and the base and console "lock" together and are synchronized. This prevents more than one

console from working with a single base station. This means that someone cannot use another

SoundStation2W console to intercept and listen in on a given phone call. The authentication key

between the base and console is verified every time the console goes off hook.

64-bit Voice Encryption

Once a call is established, voice packets traveling between the base station and console are

continuously encrypted using the DECT Standard Cipher (DSC) encryption algorithm. This

encryption algorithm was developed under the ETSI standardization body. Every time a call is

established a new 64-bit cipher key is generated during the authentication process. There are

300,000,000,000,000,000 possible keys. Voice packets coming from the base station are encrypted

and once the console receives them, the unique cipher key allows the console to decrypt the

packets. When voice packets are traveling from the console to the base station the process is

reversed. No encryption is present at the external telephone line connection. 64-bit encryption

exists solely between the SoundStation2W base station and console.

DSS Frequency Hopping Implementation

The SoundStation2W operates in the 2.4 GHz ISM frequency band (2.401 – 2.483 GHz). There are

95 channels in this band (863 KHz slots). Voice signals are digitized (packetized) and transmitted

over these 95 radio channels using a spread spectrum technique called frequency hopping. This

technique was originally developed for secure military communications. During this frequency

hopping, the radio hops 95 channels 100 times per second (every 10 ms) in pseudo-random

sequence. Voice packets will be dynamically allocated to the best 75 quality channels. Frequency

hopping coupled with digitized voice and dynamic channel allocation provides SoundStation2W

users with unprecedented reliability and quality. Plus, it makes it all the more difficult for someone

to intercept and listen in on a conference call taking place over a SoundStation2W.