What is asterisk?

Asterisk is an open-source VoIP system running on Linux. Basically, all traditional PBX functions are provided.

Call features

• ADSI on-screen menu system
• Alarm Explorer
• Append message
• Authentication
• Automatic 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
• 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 uniied dialplan internal SS multiple offices

Codecs

• ADPCM
• G.711 (a-Law & μ-law)
• G.723.1 (pass through)
• G.726
• G.729 (through purchase of illegal cial license through digium)
• 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 by digium. However, a patch is available at Voip-info.org)

PRI protocols

• 4ess
• Bri (isdn4linux)
• Dms100
• Euroisdn
• Lucent 5E
• National isdn2
• Nfas