To check for availability of a new installation archive, do the following:

cd /usr/local/FlashphonerWebCallServer/bin
sudo ./webcallserver check_update

Updating the server can be done with the following commands:

cd /usr/local/FlashphonerWebCallServer/bin
sudo ./webcallserver update

To start the update you will need to confirm stopping the server.
If a new installation archive is available, it is downloaded to the /tmp directory and the update of the server is then started using install.sh -silent.
After the update completes, an update message is shown and the server is started.