Since the free beer Axon PBX I'm using to build an SIP PBX server is missing a feature that I need (namely, include a user in a group extension although he's registered on a remote commercial VoIP provider so as to be notified of calls on his GSM cellphone), I need to look at alternatives.
Besides the following, do you know of free beer/speech softwares to build a PBX server?
- Asterisk (Windows version too old)
- sipXPBX (Linux only)
- SIP Express Router (SER)
- Brekeke (SIP server free for personal use; PBX server commercial; Java)
- Yate (Linux, Windows; Status?)
- FreeSwitch (Status?)
- uCasterisk (Status?)
- Bayonne (Status?)
- PBX4Linux (Status?)
- YXA (Status?)
- OpenPBX (Status?)