Hello Dantemm,
Let me answer your points in order. For the most part, I will also
equate VOIP with IP Telephony - the desire to provide telephone
quality services on an IP based network. There are other VOIP areas
that do not appear to be relevant to your query. If this is NOT
correct - let me know so I can correct the answer.
#1. The deficiencies / limitations of non-IP based systems such as
traditional PBX systems and Centrex based Systems from phone
companies. Ideally these deficiencies / limitations would have a
quantifiable cost.
The factors are not necessarily deficiencies rather than a lack of
features. Some of these features are being demanded today by customers
and thus become "deficiencies". For example:
- growth in distributed (or offshore) staffing by many companies
require an adaptable system for call routing and toll avoidance. A
traditional PBX cannot do this (or do so in a limited manner) but VOIP
can.
- automatic reconfiguration during staff moves. If I pick up an IP
telephone and move it into another office, the phone number moves with
the phone. I have been told (second or third hand) that the costs of
staff moves for the phone system can run up to $100 per person with a
PBX.
The adoption of VOIP also allows many organizations to consolidate
staff. The telephone staff gets merged with the IT group with a
headcount reduction.
#2 - Overview of the concept of VoIP
The basic concept is you replace a circuit based system of a
traditional telephone system with one that uses packet switching
instead. The primary saving is with the bandwidth necessary to
implement a set of calls. Let's use a simple example to illustrate the
concept:
- each traditional phone call uses a 64 Kbit/second circuit for the
full duration of the call.
- during a VoIP call, the periods with sound take up to that same 64
Kbit/second but periods of silence or perhaps a constant tone
(assuming data compression) would take much less.
A packet switching network (VoIP) can thus carry far more calls on the
same line as a circuit based system (traditonal phones).
A long (and thus detailed to being technical) set of concepts for VoIP
are described at Cisco at
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4224/sw_confg/voipintr.htm
Several good white papers with introductory and slightly more advanced material at
http://www.hippoinc.com/whitepapers/index.htm
Many more sites have good summaries but a quick search using
voip concepts
will list them.
#3 - The technical workings of VoIP with an emphasis on SIP
The Cisco paper I referred to in #2 appears to cover the overall
concepts but does not cover SIP in any detail. For SIP - and a VERY
detailed look at VOIP, I suggest viewing
http://vvv.it.kth.se/edu/Ph.D/2G5564/VoIP-2003-20030123.pdf
which is a 1.8 Mbyte PDF that appears to be the lecture notes for a
course. It is huge - over 300 pages long and the section on SIP takes
about 75 pages. If you don't get what you need from this reference -
let me know so I can search some more.
#4 - Benefits VoIP provides organizations
The primary benefit is savings in operational costs. Almost any
moderate to large organization can save money by adopting an VoIP
system. As noted in #1, there are additional features that are also
available or enabled by VoIP which may or may not be a benefit to a
particular company (or government agency).
A quick example I read about recently (sorry - I don't have the
reference) is a small city government in California that had an old &
aging PBX that finally died. They did not have any alternative - they
had to put something in place right away. They chose a VoIP solution
to replace the PBX and got the offices back up again. Subsequently
they are looking at a number of new features such as toll avoidance
where they use existing networks and a small point of presence in
Sacramento / Los Angeles to eliminate most toll calls. In this case -
the benefits are changing over time for this government organization.
#4 - Common pitfalls of VoIP installations as well as areas of concern
(like dialing 911)
A few of the more important ones are:
- lack of adequate design / capacity
- improper tuning / QoS settings
- when problems occur - lack of proper analysis tools to isolate the
problem and fix it
there are several others but a search using
VoIP problems
VoIP "top ten" problems
and similar phrases will find pages that provide similar problem / concerns.
The concepts required for 911 services are certainly a concern but can
be handled transparently for a number of sites - simply because the
site is small enough to be considered a single facility and you route
the 911 calls through a more traditional (e.g., backup) connection
(which will signal the proper address information). You DO have a
backup connection that works - even when the power is off, don't you?
I have worked in several facilities where there are hard line
connections that work even when the PBX is off and VoIP won't make
that problem go away.
For a little more historical look (and since a lot of concerns have a
basis in past performance), check out the outline for a (for fee)
report at
http://www.mindbranch.com/listing/product/R1-1478.html
which summarizes a number of concerns / problems for VoIP suppliers to
overcome. I mention this - not to buy the report but to help answer
your concern point.
#5 - The QoS needs of VoIP on a network
Well - you need "Quality of Service" or QoS only when your network is
somehow inadequate for the demand. Going back to the Cisco reference,
if the jitter becomes excessive, people are going to be annoyed with
the telephone system. Remember - the users of the telephone expect it
to act just like a circuit based system where the connection is
"always on".
So - if you have a dedicated VoIP network and your load is always less
than your network capacity, you never need QoS. You only need QoS when
you have to prioritize (or ration) the capacity to the benefit of some
protocols and to the detriment of others. In other words, by turning
on QoS capabilities in your network equipment, you prioritize the
Voice messages to the detriment of Data messages. The data users won't
notice they get delayed (unless your network is REALLY inadequate) and
the voice users will be happy.
For some additional references with good information, check out
http://www3.gartner.com/resources/111700/111777/111777.pdf
which is a report done by Gartner about two years ago on VOIP and
related technologies.
You may also want to attend a seminar on network problems such as
http://www.interop.com/lasvegas2004/conferences/?s=program_sessions_fm&programid=164
which will be in Las Vegas in May.
For a little humor - look at #8 on the "top ten" list of fads at
http://www.kuro5hin.org/story/2003/11/14/173126/56
Look at a menu on the right (you may have to scroll down) with a set
of VoIP articles:
http://www.cioupdate.com/trends/article.php/11047_3327851_2
Don't hesitate to use a clarification request if any part of the
answer is inadequate. Good luck with your work.
--Maniac |
Clarification of Answer by
maniac-ga
on
16 Apr 2004 06:07 PDT
Hello Dantemm,
There is a lot of general cost information on VoIP, but little
specifics. For example:
http://www.vocaltec.com/html/White_Papers/VoIP%20Cost%20Advantages%20-%20NEW.pdf
talks in terms of reduced equipment, improved granularity in
deployment, and similar factors. From that and understanding the costs
of that kind of equipment, you could produce a cost savings for a
situation - but a lot of additional work is needed. Another - somewhat
humorous article is at
http://www.voip-news.com/select.htm
which goes into more detail on concerns with IP deployment and less on
actual cost savings.
However, digging a little more fully found a few sites such as
http://www.siemensenterprise.com/attachments/company/va_cost_comparison.pdf
which describes a specific situation. The last page has some specific
cost factors used in the analysis. It goes through the general
approach as well and can certainly be used as a guide for your
situation. Note - it is provided by an equipment supplier so the
findings will likely have some bias.
Here is one site that describes a similar situation (moving a
telephone customer from one service provider to another) . It claims
the costs are $200 to $400 per customer.
http://www.americasnetwork.com/americasnetwork/article/articleDetail.jsp?id=44530
There are also companies providing both free and for fee calculators
that estimate resources /costs for implementing VoIP. For example
http://www.erlang.com/calculator/
has a set of eight calculators for free and
http://www.erlang.com/voipselect.html
is a more comprehensive (and customizable) package for $149. There are
some additional documents describing the terms they use and the tools
at
http://www.erlang.com/support.html
Getting to cost savings for your specific situation will require some
follow on analysis. Using the examples I provided before:
- call routing (save cost of existing lines that you won't need with
the new system)
- toll avoidance (some fraction - may be 50% or higher - of toll
costs are avoided)
- automatic reconfiguration (I stated $100 and the other reference
says $200-$400 each)
- staff consolidation (NOTE - savings only if you do a staff layoff
or reassign existing staff to get more income)
These examples (and similar ones for your situation) should give you a
framework to do that analysis.
For reference, search phrases used included:
operational cost comparison voip
operational specific costs voip dollar
--Maniac
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