OPNaskozia
19" rack mountable Askozia Telephony appliance
Askozia, is a complete embedded telephone system firmware. It is incredibly easy to use, runs on a multitude of hardware offerings and speaks ISDN, Analog and VoIP.

It is fully featured with, Auto-Provisioning, Voicemail via e-mail, Fax support, conferencing, transfers, call parking, music-on-hold, multilingual configuration interface, multilingual audio prompts, regional tone settings...
it's all there.

All versions of OPNaskozia run the premium Askozia version and are delivered with a free copy of the Askozia handbook.