When vpn_configuration is set to 1, the Voice Client routes everything via the VPN network. The important points related to VPN usage only follow:
If VPN is in a disconnected state and Voice Client is brought to the foreground, the Voice Client notifies in the notification bar, and the message is displayed as shown in the below screenshots:
Voice Client cannot be used if VPN is in a disconnected state.
When VPN is in a connected state and if Voice Client was already loaded with the profile and registered with the PBX:
In such cases, whenever VPN is disconnected, the Voice Client is de-registered with the PBX.
The Voice Client always monitors the VPN status.
Depending on the kind of configuration provided at the Voice Client and Extension Manager end, Voice Client is registered or re-registered with the PBX when VPN has connected.