General

When using a cordless phone, the user expects the best possible voice quality and excellent reliability.

The DECT (Digital Enhanced Cordless Telecommunications) standard has a high level of acceptance and fulfils those requirements. In contrast to WLAN, DECT uses its own reserved frequency range. Because DECT works in the 1.9 GHz range, the high frequency propagation characteristic is better than with WLAN, and this results in a greater coverage. So, with VoWLAN, more access points are also required than with DECT. WLAN was originally developed for data transmission by terminals whose location does not change. With VoWLAN, however, the wifi telephone's location is constantly changing. So VoWLAN must be capable of handing the connection over from one access point to the next access point (handover/roaming). This must be possible with no noticeable interruption to the connection (seamless handover). This feature is particularly important for installations in large enterprises in which multiple access points are being used.

The chapters that follow will show how this type of VoWLAN network has to be configured and set up so that the main quality features demanded of cordless telephony can be provided. We shall use the bintec be.IP™ oder be.IP plus™, bintec W2003ac-ext™ WLAN access point, a bintec RS123w™ as WLAN controller, and the bintec-certified Ascom i62™.