Association; User Authentication - ASCOM VoWiFi System System Description

System Description
Ascom VoWiFi System
4.3.2

Association

Before the authentication can take place, the mobile device need to be associated with an
AP.
Each AP in the network transmit beacons that the mobile devices listens to. The mobile
device, in this case a VoWiFi handset, sends an association request to the AP with the
strongest RF signal. By comparing the ESSID, the AP verifies that the VoWiFi handset is
allowed to associate with the AP and sends an acknowledgement. Communication between
the IP handset and the AP is hereby established.
4.3.3 Authentication
Authentication is the process of verifying the credentials of a mobile device trying to access
the network. In a secure WLAN system additonal user authentication can be handled by a
RADIUS server.
When the association process between the VoWiFi handset and the AP is finished, the
VoWiFi handset sends an authentication request. The request is forwarded by the AP to the
RADIUS server where parameters such as User Name and password are verified before
network communication is allowed.
Once authenticated, the information is stored in the Controller (in a Controller-based
solution) to shorten the process.
Note: The authentication method is dependent on the security level set for the system. The
VoWiFi handsets can be used in systems with no security, as well as in systems with WPA-
PSK security.
IP-PBX
Figure 10. Association and Authentication
13 December 2010 / Ver. F
Figure 8.
IMS2/
Unite CM
WinPDM
VoIP Gateway
PBX
VoWiFi Handset
RADIUS
Controller
Server
IP Backbone / LAN
AP
AP
TD 92313GB
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