The configuration file that you can download from the admin interface of the PBX assumes that your gateways or IP phones belong to a DHCP network. However, if you assign a static IP to your device you also need to assign:
1) a gateway within your network (e.g. 192.168.1.254) that is needed to reach Cluana’s servers;
2) at least one DNS server (in place of the google's standard DNS servers 220.127.116.11 and 18.104.22.168).
These are required to resolve the hostname of Cluana’s server (e.g. "mintaka.cluana.com") into a valid IP address.