IPBX, Asterisk / trixbox, designed to deliver traditional PABX call services over Internet Protocol. It can interact with existing PSTN (Public Switched Telephony Network) networks using anlog (FXO) and digital (BRI, PRI) PCI cards. It is also possible to have an analog and a digital VoIP gateways to interconnect IPBX to PSTN network.  Asterisk is the world’s leading open source telephony engine and tool kit. Offering flexibility unheard of in the world of proprietary communications, Asterisk empowers developers and integrators to create advanced communication solutions...for free.
Asterisk® is released as open source under the GNU General Public License (GPL), and it is available for download free of charge. Asterisk® is the most popular open source software available, with the Asterisk Community being the top influencer in VoIP. Asterisk can be configured as the core of an IP or hybrid PBX, switching calls, managing routes, enabling features, and connecting callers with the outside world over IP, analog (POTS), and digital (T1/E1) connections. Click here for Asterisk features...  trixbox is a line of Asterisk-based IPBX products designed to meet the needs of companies from 2 to 5000 employees. trixbox is an open telephony platform that combines the best of the open source telephony tools into one easy-to-install package. Based on an enhanced LAAMP (an open source bundle of Linux, Apache, Asterisk, mySQL, and PHP), the trixbox dashboard provides easy to use, Web-based interfaces to setup, manage, maintain, and support a complete IP-PBX system.. Click here for trixbox features ...
All installation services will be delivered online only. Asterisk / trixbox IPBX has many different types of interconnection model. - To connect with a PSTN operator we can use FXO, BRI, PRI PCI cards as Digium, Sangoma ... or use FXO, BRI, PRI VoIP gateways as Audiocodes, Patton, Cisco...
- Users can have a VoIP phone, Soft phone or Analog phone connected to the FXS VoIP gateway.
 Standard Enterprise IPBX Applicaiton Call features ADSI On-Screen Menu System
Alarm Receiver
Append Message
Authentication
Automated Attendant
Blacklists
Blind Transfer
Call Detail Records
Call Forward on Busy
Call Forward on No Answer
Call Forward Variable
Call Monitoring
Call Parking
Call Queuing
Call Recording
Call Retrieval
Call Routing (DID & ANI)
Call Snooping
Call Transfer
Call Waiting
Caller ID
Caller ID Blocking
Caller ID on Call Waiting
Calling Cards
Conference Bridging
Database Store / Retrieve
Database Integration
Dial by Name
Direct Inward System Access
Distinctive Ring
Distributed Universal Number Discovery (DUNDi™)
Do Not Disturb
E911
ENUM
Fax Transmit and Receive (3rd Party OSS Package)
Flexible Extension Logic
Interactive Directory Listing
Interactive Voice Response (IVR)
Local and Remote Call Agents
Macros
Music On Hold
Music On Transfer:
- Flexible Mp3-based System
- Random or Linear Play
- Volume Control | Call features Predictive Dialer
Privacy
Open Settlement Protocol (OSP)
Overhead Paging
Protocol Conversion
Remote Call Pickup
Remote Office Support
Roaming Extensions
Route by Caller ID
SMS Messaging
Spell / Say
Streaming Media Access
Supervised Transfer
Talk Detection
Text-to-Speech (via Festival)
Three-way Calling
Time and Date
Transcoding
Trunking
VoIP Gateways
Voicemail:
- Visual Indicator for Message Waiting
- Stutter Dialtone for Message Waiting
- Voicemail to email
- Voicemail Groups
- Web Voicemail Interface
Zapateller Computer-Telephony Integration AGI (Asterisk Gateway Interface)
Graphical Call Manager
Outbound Call Spooling
Predictive Dialer
TCP/IP Management Interface Scalability TDMoE (Time Division Multiplex over Ethernet)
Allows direct connection of Asterisk PBX
Zero latency
Uses commodity Ethernet hardware
Voice-over IP
Allows for integration of physically separate installations
Uses commonly deployed data connections
Allows a unified dialplan across multiple offices | Codecs ADPCM
G.711 (A-Law & μ-Law)
G.722
G.723.1 (pass through)
G.726
G.729 (through purchase of a commercial license)
GSM
iLBC
Linear
LPC-10
Speex Protocols IAX™ (Inter-Asterisk Exchange)
H.323
SIP (Session Initiation Protocol)
MGCP (Media Gateway Control Protocol
SCCP (Cisco® Skinny®) Traditional Telephony Interoperability E&M
E&M Wink
Feature Group D
FXS
FXO
GR-303
Loopstart
Groundstart
Kewlstart
MF and DTMF support
Robbed-bit Signaling (RBS) Types
MFC-R2 (Not supported. However, a patch is available) PRI Protocols 4ESS
BRI (ISDN4Linux)
DMS100
EuroISDN
Lucent 5E
National ISDN2
NFAS | |
IPBX - Asterisk / trixbox 
