4PSA VoipNow is the leading Linux IP PBX server software for Hosting and Internet Service Providers, businesses of all sizes, call centers and residential users. With multi-tenant software architecture 4PSA VoipNow delivers hosted PBX services or can be used as a standalone PBX server in a company office.

4PSA VoipNow Express free edition offers standard PBX features and supports up to ten phone extensions, while Professional edition offers increased scalability and advanced PBX features: IVRs, group management, calling cards, callback, remote conferences and call queues.

Standard PBX features:
SIP and IAX channels support
- Caller ID / Call management / call recording / Voicemail / DND (do not disturb) function / call cascading / ring groups/ music on hold/ DID management / call monitoring

Advanced PBX features

- Intelligent cost call routing and PTSN fallback / Incoming call rules / Local or public conferencing / Fax and voicemail to Inbox / Auto attendant (IVR) with text2speech / Call center ready (call queues with sophisticated distribution algorithms and advanced graph reports and statistics) / Callback service / Calling card / call screening


User management

- Multi-tenant software architecture / Four levels of control for hosted services (admin, reseller, client, extension) / Web based interface / group management /Individual permissions and limits for each account / SOAP API for integration with third party apps

Billing and reporting

Real time billing engine / Time intervals management / Prepaid and postpaid billing plans / Calling card billing / Callback billing / Call center grade queues report

The system can sustain several hundred extensions even on an entry level server.
The ZIP file contains a Linux shell installer. You can also download the ISO, VMware Image or Virtuozzo/OpenVZ.
For more details about the software installation, check:
http://www.4psa.com/getvoipnow