Citywide Voice and Video Using Asterisk and Open-Source

Embedded Hardware

Kelvin ChuaChief Technology Officer NEXTix Inc.Astricon 2009

Taguig City, PhilippinesHigh monthly recurring telecommunication costs

Legacy EOL PABX

Non-resilient single point of failure

Flexibility issues

No contact-center features

No cdr reports and call statistics

No centralized dial plan

Highly dependent on PSTN infrastructure

Project AdvantagesVirtually unlimited phone lines/numbers

Centralized communications

24/7 Inquiry and emergency hotline service

Security and reliability

Scalability and Extensibility

Faster deployment

Ease of operation

Project Design and Implications

Less interconnection with the PSTN

Network and application layer redundancy

QOS on all data nodes

Remote site contact-center integrated

Network monitoring system

Disaster resiliency

And most importantly, least cost :)

Network Diagram

Project Implementation: Data Network

Choice of technology: 802.16e WiMax

Multiple Star Topology

QOS on both the client and central nodes

VLAN tagging across the wired and wireless network

Project Implementation: Telephone Network

Initially 2 ISDN PRI from 2 different providers as the

main PSTN interface and an ITSP link via SIP

2 Digium 24port for interim connectivity to legacy PABX

A minimal number of landlines were maintained for

redundancy in far-flung areas. These are connected to

embedded asterisk-based appliance.

Project Implementation: Asterisk Servers

4 Asterisk servers in 2 physical locations

Clustered dialplan (primary and secondary proxy)

Fax dispatch system based on hylafax and iaxmodem

Autoprovisioning

Mysql backend

Support for SIP video endpoints and video conferencing

Project Implementation: Embedded Appliances

Based on Blackfin DSPs

Fanless, Solid-state open-hardware design

Supports FXO, FXS and PRI

Embedded firmware with GUI

Clustered dialplan

Project Implementation: Network Monitoring System

Based on Cacti open-source graphing solution

SIP/IAX peers online/offline as well as concurrent

SIP/IAX/Dahdi(Zap) calls

System voicemail

Heartbeat and threads

SNMP

Automated triggers and alerts

Project In Action:

Sudden ease in remote inter-department calls

Unauthorized toll calls were eliminated

Government services became more efficient

All incoming calls, including death threats, extortion

and corruption activities are now monitored

Cost savings on monthly recurring telecom charges

Proven disaster survivability

September 26, 2009 at the height of tropical storm “Ketsana”. Asterisk saved a lot of

casualties, serving thousands of calls a day for the city government's contact center.

Thank You!

For more info:

kelvin@nextixsystems.com

http://www.nextixsystems.com

http://www.nextixsystems.com/citywide-telephony.php

http://www.nextixsystems.com/citywidefactsheet.pdf