Remote MT300N - OpenVPN to connect to local IP range

Just received 2 MT300N and these are very cute… very nice

 

My challenge: VOIP server on location A in IP range 192.168.1.xxx and Telephones on location B (having fixed 192.168.1.xx addresses) that need to be connected to location A via OpenVPN. After a powerfailure everything should reconnect automatically. It is no issue if all internet requests are redirected via location A. Location B has an IP range 192.168.0.xxx.

Open VPN is working correctly already. What is needed that phones (192.168.1.xxx) on a 192.168.0.xxx can connect to the server?

Need some guidance

Sorry I don’t have experience on VoIP.