[Asterisk-biz] Open Source IP Centrex

[Tim Schroeder]

Tamer,

About a year ago I did a feasability study on the prospects of an IP Centrex
operation here in the UK, in fact it's something I'm still looking at doing.
I was looking at it from a pure Cisco perspective at the time, as my
experience is heavily Cisco-related.  The biggest commercial problem was
cost of WAN bandwidth into customer sites, however with the more recent
availability of relatively low-price and low-contention ADSL circuits and
with widespread SDSL not far off it changes everything.  If you're looking
at 1000 sites at 50 users then b/w isn't much of a problem for you, with
g729 @ 24kb per call you can have 10 concurrent calls on a 512k/256k ADSL
circuit which for 50 users gives you 5:1 concurrency which should be fine.
Obviously if your cost model can support leaselines/fractional-T1 then
that's even better.  QOS, resiliency, congestion management, network
monitoring & WAN profiling are all critical to a project on the scale of
what you're suggesting.  I'd want IPsec VPNs into each customer site for
management but probably wouldn't run the audio streams through them.

In answer to your questions,

Software - SIP switch such as Asterisk for SIP phones.  A good network
management app with support for VoIP.  Redundant Linux-based syslog, RADIUS,
SNMP, SQL apps.  Proactive fraud prevention.  Billing.  Web-based
self-provisioning.  Call reporting (web, email, pretty graphs for the IT
director, etc).  I'd use RADIUS with an SQL backend for the call
authentication and accounting (CDR).

Hardware - If you're talking centralized H.323 gateways I have to admit I'm
a Cisco fan but then again I haven't worked with many other gateways.  Ours
at UK Voice are all Cisco-based.  Yes it comes with a higher price tag but
it's a one-off capital investment and in the big picture it isn't
significant.  There's a difference between buying Cisco kit and paying Cisco
prof services to do it for you!  The Cisco gateways can also provide
conference and codec transcoding capabilities, IVR for calling card apps,
T.37 for fax-to-email, etc.  I assume you'd offer voicemail/unified
messaging but Cisco is too pricey in this area.
Phones - Use SIP only and select a range from cheapies up to flashy color
touch screen models.

Professional Services - If I can be so bold.... contact me on or off list
about how I might be able to help.  I'd be very interested in getting
involved in this, and I could provide most of what is needed, other than the
customer base!  I have Cisco CCIE and IP Telephony qualifications and 10
years experience in the field.  When I worked as a consultant for a Cisco
direct partner, I did this kind of thing many times albeit on a much smaller
enterprise-level scale.

Best regards,

Tim Schroeder
UK Voice Ltd

-----Original Message-----
From: asterisk-biz-admin at lists.digium.com
[mailto:asterisk-biz-admin at lists.digium.com]On Behalf Of
tamer at zanaty.net
Sent: 19 August 2004 14:23
To: asterisk-biz at lists.digium.com
Subject: [Asterisk-biz] Open Source IP Centrex


Dear all,

I would like to ask the experts in the mailing list about the best Scenario
to build an open source IP Centrex operation, what open source software are
recommended and what hardware would be required, and what professional
services and where to find them.

The business requirements is to build from scratch an ASP telecom operation,
to provide IP Centrex services to 1000 customer location with an average of
50 user in each location, services will cover enterprise features, long
distance and international calls, conferencing bridges and others

Your advice is highly appreciated, as our alternative would be giving our
money to giants like Cisco or Nortel and turn our selves to life time slaves
for these masters :)

Thank you in advance for your time

Best Regards,

Tamer Zanaty
Director of Telecommunications
Star Communications


_______________________________________________
Asterisk-Biz mailing list
Asterisk-Biz at lists.digium.com
http://lists.digium.com/mailman/listinfo/asterisk-biz