As maybe you already know Snom phones support a VPN feature trough the OpenVPN software.
OpenVPN is a very powerful tunneling solution and offers a wide set of features.
One of the most useful and less known feature is the support for multiple remote VPN endpoint.
As documented in the man page you can define more than one remote statement in your vpn.cnf.
The OpenVPN client will try to connect to a server at host:port in the order specified by the list of --remote options.
Using the <connection> configuration section you can even define multiple connection profile per each remote endpoint.
Here is a very simple vpn.cnf example using more than one remote endpoints:
client tls-client dev tun proto udp remote server1.foo.com 1194 remote server2.foo.com 1194 remote server3.foo.com 1194 resolv-retry infinite nobind persist-key persist-tun ca /openvpn/myca.crt cert /openvpn/clien.crt key /openvpn/client.key ns-cert-type server ping-restart 60
For more informations and details we point you to the official OpenVPN documentation: