Route All The Internet Traffic From My Android Voip App To My Own Vpn Server

We have set up our own VPN Server and want to route all the traffic from our VOIP android app through this server. But all the solutions I have seen thus far use the vpn service cl

Solution 1:

VpnService does not need to apply to the whole device. See: VpnService.Builder.addAllowedApplication (available with API 21 - 5.0):

Adds an application that's allowed to access the VPN connection. If this method is called at least once, only applications added through this method (and no others) are allowed access. Else (if this method is never called), all applications are allowed by default. If some applications are added, other, un-added applications will use networking as if the VPN wasn't running.