The document provides answers to four frequently asked questions about PVDTN, an integrated voice, fax, and data network solution. 1. It explains how PVDTN saves costs by replacing traditional telephony networks with a circuit-switched voice/fax network and separate IP data network over the same leased lines. This reduces total communication costs compared to maintaining separate voice and data networks. 2. PVDTN maintains separate networks that are managed independently, so existing teams can continue their roles without conflict. 3. PVDTN is more bandwidth efficient than VOIP alone and ensures sufficient bandwidth to avoid call blocking or quality issues, further reducing costs compared to VOIP implementations. 4. Web collaboration

1. FAQ 1
How are savings made in PVDTN?
The voice to non-voice (fax and data)
communications cost ratio varies as under
based on statistics collected for various MLOs
(multi-locational organisations across the
world.
80:20 for the most developed countries
95:5 for developing countries
97:3 for less developed countries
Since for the same unit of time 60 times more
information can be transported as data the
Volume ratio would look like
80:1200 for the most developed countries
95:300 for developing countries
97:180 for less developed countries
There is one other ratio the inter-locational (or
intra-company) communications costs to total
communication costs. This could vary from
about 40% for small and less inter-active
MLOs (multi-locational organisations) to
80 to 90% for large and highly inter-active
MLOs.

2. FAQ1(Contd.)
Thus if the total communication (voice and data)
costs of a company like yours is X the cost of
voice communications will be around 95% and
that of data around 5%. The integrated voice-
data intra-net will carry only the inter-locational
voice traffic and the total data traffic which is
mostly internal. Even external email will be
passed through this network to be conveyed to
the internet gateway through the STS system.
The total cost of inter-locational communication
of a company is = T + D, where T is the inter-
locational telephony and fax cost and D is the
data communications cost. In this case T will be
say 0.8 x 0.95 X = 0.76 X ; and data com cost
will be 0.05 X.
What PVDTN does is that it eliminates T, by
adding a percentage of D to D. Thus in place
of T+D as you have now, for inter-locational
communications costs, you will have D + d ( a
percentage of D) for total inter-locational
communications costs with PVDTN. Further
presently T varies with increased usage and
consequently (T + D) increases year by year
with increased usage. (D + d) on the other
hand will be a fixed per annum cost for
unlimited usage. There are no usage charges.

3. FAQ 2
In our company the voice and fax
services are looked after by one group,
and the data services are looked after by
another group. Since PVDTN is an
integrated voice / fax / data network what
will happen to this arrangement?
In PVDTN over the same point-to-point leased
line backbone we have two separate and
distinct networks running.
A circuit switched network for voice and fax
communications through the VDPS (EPAX
with E&M trunk cards).
A packet switched IP network through the
data routers sitting on the computer LAN at
each location.
The bandwidths for each network are provided
by the channels splitter at each location.
The above are clearly explained in Slide 2, of
PVDTN Presentation.
Thus your present voice communication team
will look after the circuit switched voice and fax
network for inter-locational communications and
the PSTN infrastructure already in place.
The IT / data communications team will
administer the packet switched IP data network
through the data routers and the PVDTN WAN,
and also the Internet connectivity
Thus there is no conflict of roles or interest of
either group of people.

4. FAQ 3
We have already implemented voice
integration over our existing data network
using VOIP (voice over IP). How can PVDTN
improve on this?
In VOIP (voice over IP) the actual bandwidth
required per each call through the WAN is 90 to
100 kbps. In the circuit switched network the
bandwidth required for each call through the circuit
switched WAN is either 12.8 kbps or 24 kbps
depending on the multiplexers (channel splitter)
being used.
Thus considerably larger link bandwidth is required
for VOIP leading to higher operating costs. Use of
PVDTN integration will reduce the link
bandwidth and hence the operating cost.
Irrespective of VOIP or PVDTN integration the
number of simultaneous calls to be provided in any
WAN link is determined by Erlang loading, which is
the number of extensions to be served by each
trunk (WAN call). This could vary from 1:6 (for very
busy locations), to 1:10 (for normal locations as in a
standard PSTN network). For most multi-locational
organisations (MLOs) 1:8 is a good Erlang loading
ratio.
Thus if there are 96 users of NET telephones in a
location based on Erlang loading of 1:8, there
should be 12 simultaneous WAN calls or trunks
provided for. These may be distributed over all the
lines terminating at the location.

5. FAQ 3 (Contd.)
The total bandwidth required for evacuating
these simultaneous WAN calls will be 1200
kbps for VOIP and 154 or 288 kbps for PVDTN.
If the appropriate bandwidths are not provided
in VOIP it will amount to bandwidth jamming
and resulting unsatisfactory speech quality.
And in PVDTN it could cause blocking of
communications.
Provision of the appropriate bandwidth ensures
unblocked communications in PVDTN and
satisfactory speech quality in VOIP.
In most VOIP implementations this aspect is
overlooked resulting in bandwidth jamming and
unsatisfactory speech quality.
This is what prompts the NET phone users to
fall back on their PSTN phones to speak to
their colleagues in other organisation locations,
increasing telephony costs.
In PVDTN bandwidth provision is always
optimum resulting in unblocked toll quality
(normal telephone like) speech. Thus PSTN
calls to other company locations are totally
eliminated.

6. FAQ 4
How do we run our Web based collaboration tools
on PVDTN?
♦ PVDTN is a combination of two parallel
networks.
♦ A circuit switched network for normal
telephony and fax communications
(synchronous communications)
♦ An IP packet switching network for data and
and other IP communications (asynchronous
communications).
♦ All collaboration tools and software will run on
the IP network for collaboration within the
organisation, with the software residing in a
server housed within the Intranet. This may be
done using Novell Teaming and Conferencing ,
Microsoft Share Point, etc.
♦ For collaborative work with the outside world –
clients, vendors, consultants, the Internet would
be used through the IBN (Internet Browsing
Nodes). For this there are two options.
♦ Use Web based meeting portals like
Mediatone Networks Webex (there are
several other similar shared collaboration
solutions portals).
♦ Set up your own Web based collaboration
server in the Company’s Web based Public
server and carry out collaborative activity
with the Company’s clients ,vendors,
consultants, business partners. This may be
done using Novell Teaming and
Conferencing, Microsoft Share Point, etc.