A Very Concise Introduction to Open Source Voice-over-IP William Emmanuel S. YU Novare Technologies
Agenda Introduction Voice over IP Open Source Voice over IP Getting Started Conclusion On the Side...
Introduction
Introduction Growth in Voice-over-IP (VoIP) Usage VoIP will account for 75% of the world's voice traffic by 2007 (Frost and Sullivan 2005) Skype built a subscriber base of 75 million in 2.5 years (Frost and Sullivan 2006) ibasis carried 7.7 billion minutes of voice traffic in 2005 alone (Frost and Sullivan 2006) The Philippine Call Center industry is carrying at least 3 billion minutes a month (DTI 2005) VoIP is moving from wholesale to residential
In the Beginning... In 1870, Alexander Graham Bell and Elisha Grey independently invented the Telephone Depends on whose version of history we are looking at It was invented to allow for voice-based communications
Old School Telephony
The Problems Concurrency Only one call per line Last Mile Concurrency - Each person has to have a phone line per simultaneous call Complete Graph To connect everybody to each other there must be a circuit between everybody Trunk Concurrency Each call placed between local exchange must have one line Summary: We need a lot of wires!
Solutions Telephony Remedies Use of Trunks sharing lines between different exchanges to support calls Use of PCM and Digital Trunking ability to push more than one call per line Unanswered questions What about use of voice communications on a computer? Why have a separate device for voice and data? Why use separate wiring for voice and data? Why limit the use of digital technology to trunks?
Telephony Today Use of Trunks Use of Digital Signaling in the Trunks Most of the Last Mile is still analog
Voice-over-IP
Voice-over-IP Ability to route voice communications over the Internet Takes advantage of the fact that packet switching is more resource efficient than circuit switching Use computers as telephones
What's in it for me? Eliminate the need for costly traditional PBX systems Save on cabling use IP cabling for the entire office! Save on PBX equipment use PC servers instead Of course, VoIP phones are still more expensive Ability to create convergent applications IP-based Interactive voice response applications Merge traditional web or client applications with telephony systems
Existing Scheme
Key Ingredients VoIP Gateways, Redirectors and Proxies Gateways responsible for connecting to different networks Redirectors authenticate and handle signaling for clients and route calls to its appropriate destination Proxies authenticate and handle signaling for clients and proxy calls to its appropriate destination VoIP Clients and Softphones End-user software or hardware that handles calls
Open Source Voice-over-IP
Key Ingredients VoIP Gateways, Redirectors and Proxies Asterisk (Festival, FreePBX, SugarCRM, etc...) IPTel's SIP Express Router (SER) SIPfoundry's SIPX, OpenSER, Mobicents VoIP Clients and Softphones Ekiga (software formerly know as gnomemeeting) Mozdev Cockatoo, SFLPhone, Twinklephone Numerous options for Open Source VoIP. Numerous plug-ins and modules. It's confusing!
Asterisk Open Source SoftPBX Software Can be used as a gateway, redirector or proxy Runs on Linux and Unix OSes Typically, provides voice gateway and PBX functionality Also provides Centrex features
Ekiga Formerly known as GnomeMeeting Voice and video conferencing application for GNOME Can run on any operating system that supports GNOME Supports both the H. 323 and SIP protocols
Other Stuff into the Mix CentOS Linux Operating System and Distribution (but any flavor of Linux would do) Asterisk - Core SoftPBX and Centrex functionality Sendmail Electronic mail (for Electronic Fax) FreePBX Management Interface A2 Billing Usage and billing interface HUDLite Operator Panel VoIP Phones either hardware or software
Trixbox The Linux distribution formerly known as Asterisk@Home It is an all-in-one-distribution containing all the most common VoIP core services needs in one package Uses CentOS (RedHat Enterprise Linux derivative) as its Linux distribution core It contains Asterisk, FreePBX, Sendmail, A2 Billing, Festival and many more
Getting Started
Basic Ingredients One (1) CD-ROM Trixbox CE Get the latest available community edition version One (1) Computer This servers are your all in one VoIP server Two (2) VoIP phones Get hardware phones from Linksys, Cisco and others Or use a softphone such as Ekiga or X-Lite Optional PSTN interface cards
A Note on VoIP Hardware Codec Issues There refer to encoding technology used to compress calls Not all hard phones support codecs you want to support G.711 is ideal for LAN use (all phones support it) G.729/GSM EFR is ideal for WAN use, G.723.1 for PC use Where to get them? Microwarehouse (Linksys & Sipura Distributor) http://www.microwarehouse.com.ph/ MDi (Cisco Distributor and Systems Integrator) http://www.mdi.net.ph/
A Note on PSTN Interfacing FXO/FXS Cards Used to connect your VoIP server to direct lines Each direct line can only handle one call Some carrier have rules dis-allowing use in PBX/KTS systems E1/T1 Cards Used to connect your VoIP server to digital trunks Each digital trunk can carry multiple calls In the Philippines, comes as E1 ISDN PRI or E1R2 (E1 PRI is easier to configure)
Steps Prepare Computer Connected to necessary peripherals, ensure it has a CD- ROM drive, install PSTN interface cards (optional) Install Tribox Insert Tribox CDROM, follow instructions It is best you familiarize yourself with Linux first Initial Configuration Configure networking settings Load web-based configuration tool
Steps Web Configuration Load web-based configuration tool and login as an administrator. The password is the same as your configured root password. Go to the tools section and ensure that at least SIP and Core are selected. You can play around with the rest later. Go to the extensions section later and create an extension for your users. Client Configuration Each soft or hard phone will have their own procedure
Steps Perform Test Calls After configuring at least two locals, just do some test calls to each other That is it! - wasn't very hard right?
Conclusion
Conclusion Voice-over-IP Is a key technology for convergent voice and data networks Enable a rich set of features and VAS Provides significant cost savings in terms of infrastructure consolidation Large amount of open source software available However, it it still a complicated piece of technology with complicated tools Enabling software such as Trixbox is important
On the Side...
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References IP Telephony (John Wiley and Sons 2005) Asterisk Open Source PBX (asterisk.org) About.com: History of the Telephone Christiane Müller, Bachelor of Science & IT- System-Kauffrau, Berlin Course Web Page IETF SIP (RFP 3261) ITU-T H.323 VoIP Diagrams by Cisco