This happens because the network quality at the Komp user’s site or at the place you are might be too poor to start the conversation.
Please restart the app on your phone. If it is still not connecting, try to connect your phone to a different network (for example try using 4G if your phone is currently connected to WiFi). Restart the app after switching networks.
Restarting the Komp by unplugging the power cable for ten seconds might also help.
If this a regular occurrence, try calling from a different device on the same network. For example, if you live with someone else you can try calling with that phone, or use a tablet.
You can also test if the Komp's connection with the internet is the problem, by connecting the Komp to a different network.