Voice over Internet Protocol (VoIP) and Asterisk HOUNGUE Pélagie Contact:

Outline Introduction Enterprise Telephony : PABX The IPBX What is Asterisk? Material and software recommendations for the deployment of Asterisk solutions Different scenarios for Asterisk solution deployment Practical case of IMSP in Benin Conclusion

Introduction Why enterprises need telephony? Telephony is indispensable in conducting business and to be competitive So Companies spend lot of money to buy their own telephony switch (PABX)

Enterprise Telephony : PABX Presentation of a PABX  Definition : it is a private telephony switch.  Common Functionalities Direct dialing-in Transfer call Connection to PSTN etc  Cost between $1300 et $ (from studies conducted in Benin)

Problematic  Extremely high cost  Use of proprietary protocols Interesting and new perspectives introduced by VoIP emergence:  Possibility for the deployment enterprise telephony infrastructure using software (IPBX) Enterprise Telephony : PABX (Con’t)

VoIP Definition : carry a voice on data network using IP packets. Components

The IPBX What is a IPBX?  Software which can be installed on a PC or a server and acting as an auto-switch. Example of IPBX  Cisco Call Manager  SipX  OpenSER  Asterisk  And many more.

What is Asterisk? (Con’t) Functionalities  Voic , conference call, put in wait of calls, transfer call, call forwarding, etc. Supported Protocols and codecs  Protocols :H.323, SIP, IAX, MGCP, Skinny, etc.  Codecs : G711, G723, G726 (ADPCM ), Speek, GSM, etc.

Signalling Protocols H.323  Standard published by ITU in  Stack of protocols H.225 RAS signaling, H Call signaling (Q.931), H.245 Control signaling  H.323 elements: Terminals Gatekeepers Gateways Multiconference Unit (MCU)

Signalling Protocols SIP (Session Initiation Protocol)  Created by the Internet Engineering Task Force (IETF) in RFC 3261  Based on HTTP and SMTP SDP (Session Description protocol) RTP/RTCP  SIP elements: User Agents Proxy Servers

Example of Call transaction with SIP

Signalling Protocols IAX protocols  provide control and transmission of voip data between Asterisk servers  main goals of Minimize bandwidth usage Avoid NAT problems Support the ability to transmit dialplan information

Asterisk’s Implementation Package sources for installation Asterisk main program (Asterisk ; 2008 Apr 02)Asterisk Zapata Telephony Driver (zaptel) PRI librairies (libpri) Asterisk Sounds Package

Asterisk’s Implementation Download Files on /usr/src Extractions : # tar zxvf file_name.tar.gz Compile Zaptel, libpri and asterisk  #Cd /usr/src/name_directory  # make clean  # make  # make install  # make config

Asterisk’s Implementation Dialplan  extensions.conf in /etc/asterisk/  Fours mains parts Contexts  [general] Extensions  exten => 2223,1,Answer() Priorities  exten => 2223,1,Answer()  exten => 2223,2,hangup() Applications  Answer()  Hangup()

Asterisk’s Implementation Example of Content of sip.conf [general]  bindport=5060  disallow=all  allow=alaw  allow=ulaw  allow=gsm  language=fr [500]  type=friend  host=dynamic  username=pelagie  secret=pelagie  callerid="HOUNGUE Pelagie"  context=interne  account_code=pelagie  callgroup=1

Material and software recommendations Hardware and Software recommendations

Material and software recommendations (Con’t) Telephony hardware recommendations

Different scenarios for Asterisk solution deployment Suggested architectures  Asterisk server behind PABX Architecture

Different scenarios for Asterisk solution deployment (con’t) Suggested architectures Asterisk server in front of the PABX architecture

Different scenarios for Asterisk solution deployment (con’t) Suggested architectures  Pure VOIP architecture

Different scenarios for Asterisk solution deployment (Con’t) Suggested architectures  Interconnexion of multi sites enterprises

Different scenarios for Asterisk solution deployment (Con’t) Suggested architectures  Interconnexion of multi sites enterprises

Pratical case of IMSP at Benin Choice of the pure VoIP architecture Hardware : PC with linux CentOs distribution Some deployed services Call Detail Record Call Transfer Service of presence Call Parking Conference Voic Access voic box using web interface …

Conclusion Asterisk presents many advantages for Africa Small and Medium enterprises. These advantages are : - Cost reduction for enterprise telephony deployment - Easy administration and custom management of the IPBX - Mobility and remote work - Asterisk facility to integrate information system (Customer Relationship Management) - Etc.

REFERENCES Asterisk : The future of Telephony, Jim Van, Jared Smith, Leif Madsen

Thank You