Тhere are a number of factors to take into account when determining how many wireless headsets
can be used in a given environment. The most critical are:
1. The number of concurrent headset users.
2. The building layout and design.
3. The wireless technology and product being used and whether it operates in a wideband or
narrowband mode.
4. The presence of other devices using the same technology or frequency of operation.

Bluetooth and DECT systems do operate in different frequency bands and neither will cause the other interference. Both technologies will therefore co-exist well within any site and deployment of either can be considered separately.

DECT Summary
A key advantage of DECT is that it operates in a protected frequency-band. This means that it is NOT affected by interference from other radio signals, such as Wi-Fi or Bluetooth. In comparison to Bluetooth, DECT technology allows for the deployment of many more wireless systems within any single site, however, numerous inter-related factors do eventually limit the quantity of units that can be deployed.

Large Office Environment
Contact / Call Centre
Where users spend most of their time on calls:
70 units max
Administrative Offices
Where busy periods still result in <40% of users being on a call at any one time.
120 units max
Note
• There were successfully deployed in excess of 500 units in some very large sites. In
cases where large installations are desired, then a DECT site survey is required so specific
recommendations can be given that are unique to that site.

DECT Background
Some DECT products quote 120 channels. In fact, all DECT equipment has access to the same radio spectrum of 120 channels, but for a number of reasons deployments either much lower or higher than this figure occur. The following section provides some background to explain this:
1. Number of CONCURRENT users
A user on an active DECT call will occupy a larger part of the spectrum then a user not on a call.
An increasing amount of the DECT spectrum becomes available as the percentage of concurrent
users likely to occur at any one time reduces. This phenomenon allows for greater deployments in
areas with lower call utilisation. Unfortunately, there is still an upper limit as a DECT system when
not on an active call can still occupy a smaller part of the available spectrum.
2. The building layout and design
No office is alike. Some are open plan, some are split into sections. Some are broken up by
meetings rooms and walls, whilst others are spread across many floors. The layout and materials
used have a big impact on the extent to which wireless signals travel through a building. A concrete
wall for example reduces the path (or distance) of radio signals more than a window, whilst a big
central atrium will cause signals from one device to be seen by another much more effectively,
even when they exist on separate floors.
Such physical barriers limit the path of wireless signals, but don’t stop them. The density of
deployment will be impacted by the extent of these barriers between areas in a building.
3. The type of technology and product being used
The different technologies (DECT, Wi-Fi, Bluetooth) follow different radio protocols as defined by
international radio standards and regulations. Some of these radio technologies (such as Bluetooth
and Wi-Fi) also share the same radio spectrum. These defined protocols limit the densities that can
be deployed.
In some cases, the same radio technology can also be implemented in a different manner whilst
still conforming to the relevant specifications. The Savi Office DECT based product can achieve a
greater density of deployment as it has a feature allowing it to adapt its radio power output to its
use case. Adaption of power in this manner can result in units on the same radio channel being
spaced closer to one another and hence achieve greater density. In contrast, wideband operation
if selected on Savi Office will reduce the density of units that can be deployed. This is due to
wideband audio requiring more channel space than standard telephony audio.
4. The presence of other devices using the same technology
In any site deployment, the presence of equipment in adjacent offices or buildings also has to
be considered. Companies may have presence on only one floor of a building, but it remains
important to identify the activities and presence of technology being used by other companies on
adjacent floors as the spectrum will be shared by all.

Bluetoot Summary
For Bluetooth wireless headset usage, a general guide is that there can typically be up to 8
concurrent users (active calls) in a 15m x 20m office. Each time the area doubles, the maximum
active calls can be multiplied by 1.5.
For example: 15m x 20m office = 8 active calls
Area doubles: 30m x 20m office = 12 active calls (= 8 x 1.5)
Area doubles again: 30m x 40m office = 18 active calls (= 12 x 1.5)
There can typically be many more users (as all headset users are unlikely to actually be on calls at
the same time).

Bluetoot Background
Bluetooth uses a RF spectrum covering 79 frequencies; this does not equate to having 79 users
in one area. In fact, a Bluetooth device will hop between all/most of these frequencies in a semi
random manner during any one call. This occurs many times a second using a technique called
Adaptive Frequency Hopping (AFH), which helps reduce interference from 802.11 Wi-Fi systems.

Bluetooth Power levels
Bluetooth devices can operate at different power class levels, class 1 for high power, high range
and class 2 for lower power, lower range. Products that have the capability to operate
at class 1, also have adaptive power control enabled that allows them to operate at class 2 levels
when users are close by their desks.

For more information ot test please contact us.