It seems they had a GPL version, however they recently discontinued it; a fork of this IIUC seems to be now maintained by a community at: https://github.com/Ope

It seems they had a GPL version, however they recently discontinued it; a fork of this IIUC seems to be now maintained by a community at: https://github.com/OpenXTalk-org/OpenXTalk-Community-DPE https://github.com/OpenXTalk-org/OpenXTalk-Community-DPE