The link to download the new version is here:
ProSBC software version
You can check new features from what is unique in the software Release notes
You need to make sure the Operating system has been updated to the latest version. See: Upgrade linux packages
You need to download the license 3.3 from the TelcoBridges Dashboard and if you can install it before the upgrade, this makes the upgrade smoother.
For other versions, please contact TelcoBridges support: support@telcobridges.com