voopIX
Building the Educational
VoIP Cloud in Croatia
Branko Radojević, M.Sc.
Deputy CEO
September 2014.
(v 2.42)
CARNet – Who we are & what we do?
• Public Institution funded from National Budget
• NREN – National Research and Education Network
• Over 20 years ISP for Educational Institutions in Croatia
(schools, universities, research institutes, ministry, agencies,
public hospitals, etc.) – 3000 locations in Croatia
• Since 2004 adding more and more services for our members:
(National Educational AA infrastructure, CMS for schools, LMS for schools,
National e-learning portal, National portal for schools, Content
filtering for schools, (many, many more), and voopIX  )
• All our services are free for our member institutions
CARNet – voopIX goals
• To interconnect all our member institutions (3000 locations) to
a single VoIP cloud and to provide to them:
• Free telephony service between institutions
• Interconnect different locations of the same institution
• Let them use legacy PBXs with our system
• Provide advanced telephony possibilities available only in VoIP PBXs
• Provide free international calls to certain destinations for free
• TRY TO BE AS TRANSPARENT TO THEM AS POSSIBLE
• Open their eyes and let them discard legacy PBXs and move to VoIP
How we arrived to this idea?
voopIX - Evolution
• It all started at the University of Dubrovnik in 2004.
Proprietary phones
1x ISDN PRI
Legacy PBX
University of Dubrovnik
1x ISDN PRI
Telco
voopIX – Evolution (cont’d)
• In a matter of no time ...
Telco
University of Dubrovnik
University of Dubrovnik
DUNDi
University of Dubrovnik
University of Dubrovnik
University of Dubrovnik
voopIX – Next Step
In 2005 I’ve got
married, moved to
Zagreb and
changed my
employer to the
current one .
voopIX – Next Step (cont’d)
• CARNet – my new employer already has ordered new VoIP
PBX (normal PBX functionality + Call Center), but it’s a Cisco
Call Manager
• When it arrived, it took just few days to add an Asterisk to
CCM (connected with SIP trunk), and to bring up DUNDi cloud
and interconnect it with the Asterisks at the University of
Dubrovnik
• It proved to be reliable solution, so why don’t expand it?
• voopIX was born 
voopIX – Building the core
• We started to build
voopIX core, based on
five servers running
Asterisk positioned
in five of our largest
POPs
ZG
OS
RI
• Connections shown are
logical DUNDI peering
connections
• No clustering at this time
ST
DU
voopIX – Legacy PBXs
• Our members don’t want to throw away their working PBXs.
Some of them were purchased recently 
• We had to find a way to transparently connect them to our
system.
• Obviously, we are talking about hundreds of different
combinations of PBXs, software, cards, setups, etc.
• Telco connection is also non-unified: from R2/MFC, ISDN BRI,
ISDN PRI and some SIP trunks (recently).
• We had to put our box between PBX and the Telco connection
in order to intercept calls. Our solution should be reliable.
voopIX – Appliance (large)
• Custom designed in CARNet
PBX
• Runs Linux (debian lenny) + Asterisk
• 2x or 4x ISDN PRI voice card installed
• No hard drives
• It has custom made
failover switch that
can bypass the card
and connect back
PBX directly to Telco.
Telco
Interconnecting voopIX and PBX
CARNet
voopIX
voopIX app.
Old phones
BASIC
Legacy PBX
Telekom
operator
Interconnecting voopIX and PBX (2)
CARNet
voopIX
voopIX app.
Old phones
BASIC
Telekom
operator
Legacy PBX
HYBRID
Interconnecting voopIX and PBX(3)
CARNet
voopIX
voopIX app.
Old phones
BASIC
Telekom
operator
Legacy PBX
HYBRID
ADVANCED
voopIX - Appliance (cont’s)
voopIX - Appliance (cont’s)
FAILOVER SWITCH
NETWORK
VOICE CARD
voopIX – Appliance (small)
• Commercially available
• Runs Linux + Asterisk
• 1x FXS port installed
• 2 module slots available for line cards:
• 4x FXO, 4xFXS, 2xBRI, 2xGSM
• No hard drives, USB and SD Card reader included
• It has failover switch that can bypass two FXO and FXS ports
directly to Telco.
voopIX – Call flows (available number)
DUNDi
voopIX context
ISDN PRI
ISDN PRI
Telco
ISDN Network
CALL
Legacy PBX
CDR
(RADIUS)/LOG
voopIX – Call flows (unavailable number)
DUNDi
voopIX context
ISDN PRI
CALL
ISDN PRI
CALL
Legacy PBX
CDR
(RADIUS)/LOG
Telco
ISDN Network
voopIX - Today
1
• Around 110 locations
(our first target were the
institutions with larger
phone installations and
those considered most
interesting ones)
• We expect to double the
number until the end of
2014.
1
51
2
4
12
1
7
1
1
1
9
1
1
10
6
Problems we encountered - AOC
• AOC = Advice Of Charge (D-During, E-End)
ISDN PRI
CALL
Legacy PBX
AOC-D
Telco
AOC-E
ISDN
Network
Problems we encountered – AOC (cont’d)
• AOC = Advice Of Charge (D-During, E-End)
AOC-D
ISDN PRI
CALL
ISDN PRI
CALL
AOC-E
Legacy PBX
AOC-D
Telco
ISDN
Network
AOC-E
Asterisk Implementation Overview
(Technical Details)
Node becomes available
Telco
ISDN
Network
ZG
[iax-pbx-reg]
exten=> _38551400[5-7]XX
OS
ISDN PRI
RI
DUNDi
voopIX context
_38551400[5-7]XX
ST
Legacy PBX
Numbers: (51)-400-500 to 400-799
DU
Node becomes unavailable
Telco
ISDN Network
ZG
[iax-pbx-reg]
exten=> _38551400[5-7]XX
OS
ISDN PRI
RI
DUNDi
voopIX context
_38551400[5-7]XX
ST
Legacy PBX
Numbers: (51)-400-500 to 400-799
NAGIOS
Server
DU
Interconnection with
TERENA NRENUM.net
NRENUM.net
• Since the two systems (ENUM and DUNDi) are incompatible,
we had to build gateway service
• Outgoing calls are easy to implement, since Asterisk has builtin ENUM support that we are using
• Publishing our numbers to NRENUM tree were more difficult,
since our system is highly dynamical, and DNS zones are
more statical
• We built on top of PowerDNS software that has ability to query
not only its internal database, but also invoke script for
subqueries. So, for every query that we receive through
ENUM, we do subquery in DUNDi and return results.
Advanced Telephony Functionality
provided by voopIX
Skype to PBX
• We allow calls from Skype to any number in our system
• Often used to place calls directly from web pages
Users traveling around the World
• We provide the possibility for user traveling around the World to use
softphones which allows them to become extensions on their PBX
• It is also useful to someone working from home
• ZoIPer is a popular (and free) softphone
which is beside having SIP protocol also
provides IAX2 which has much less
problems traversing NATs
• Now available for Windows, MacOS,
iPad/iPhone, Android, Windows Phone
Centralized Services
(logging, monitoring, configuration, …)
Centralized Services
Generally, we tend to use Open Source software:
• Logging: Syslog NG
• Fault Monitoring: Nagios
• Graphs + Performance Monitoring: Munin
• Accounting: FreeRADIUS + mySQL
• Configuration+User Mgmt.+ … : Puppet
voopIX Future ?
voopIX – Future?
• Scalability problem - not yet seen, but may become an issue
• Web portal for members (billing, some setup, etc.)
• Solution for smaller institutions (Schools on small islands)
• Shown interest from other public/government institutions
• Try to animate institutions in other countries to start up similar
project and to peer with us - we’re ready to help
• Add more advanced functions to our system
Open Platform
Open Platform
• The idea here is to be able to create VoIP infrastructure on the
Open Platform, which doesn’t rely on a single vendor, single
technology or a proprietary solution
• At any time, if there is a technology or protocol that shows up
to be superior to currently used, we can move to them without
investing in new equipment or paying additional licenses
• By using central configuration, we can switch hundreds of
appliances to new system in a matter of hours
Thank you for your time !
voopix@carnet.hr
All questions and suggestions are
more then welcome.