Mobile users often change network: PrivateWave automatically detects it and reacts properly reconnecting.
Roaming between different mobile network types and between cells is managed automatically by mobile operators and does not imply an IP address change. A cell change can create a short pause (some seconds).
Roaming between mobile network and WiFi network is managed by OS on iPhone and Android, while on Blackberry and Symbian is partially controlled by application.
Network roaming between mobile and WiFi are supported and secure call continues. Users can have a short gap, under 1 seconds.
Network roaming between 2G and 3G network is supported, but depending on mobile operator and device you have a gap, variable between a few seconds up to 20. In the latter case, the secure call is automatically terminated.