Potential sources of interference

The 2.4 GHz band is used by all sorts of wireless services as well as WLAN. Most of these services are limited to small transmission power and only have limited coverage. For instance, most Bluetooth devices that we often find in office environments only have a transmission power of 1 mW, so they are not really a problem for VoWLAN. For VoWLAN operations to be free of interference it is also important, of course, that there are as few third-party access points (neighbours) in the vicinity as possible. While these third-party access points do not actually interfere, they reduce the net bandwidth. This can be improved by, e. g., changing the channel plan so that your tranmission bypasses the neighbouring access point. Particularly if a VoWLAN network is planned for a large number of subscribers, it may also be useful to install a second WLAN network with 5 GHz in order to bring the data applications to the free 5 GHz network.

In our experience, it is unusual for there to be unidentified sources of interference in VoWLAN applications if the basic rules described here are adhered to when doing the installation. Any broadband sources of interference or neighbouring access points that might lead to problems at a later stage are also identified by a site survey of the building, and counter measures can be taken in advance.