by April 14, 2006 0 comments

You read ‘VoIP’ and your mind instantly relates it to
your past Internet-telephony experiences with Net2Phone, DialPad and the likes
– gluing yourself to a computer, dealing with poor voice quality, dropped
calls and so on. There were promises of free calls across the globe, which
however, didn’t have many takers.

Applies to:ISD users
Call international destinations at cheaper rates
Google keywords:
VoIP, Internet telephony 

For those new to VoIP (short for Voice Over Internet
Protocol), it is a technology that allows you to use the Internet to carry
telephone calls.  On the contrary, telephone (landline, mobile) service
providers world-wide use  dedicated (expensive) interconnected networks,
called Public Switched Telephone Networks (PSTN), to carry voice traffic.  
Well, VoIP has come a long way since its early days-both in terms of quality
and usability.  But it still remains an acronym for Voice Over Internet
Protocol-and that is about the only thing that hasn’t changed about VoIP. 
Starting from the underlying protocols, to audio compression, the devices you
can use, to PSTN connectivity, VoIP has undergone a sea change. It is today, a
whole new experience. The spread of broadband coupled with the ease of using
VoIP (just like a regular telephone) is fueling a telecom revolution of sorts
across the globe-reducing distances and costs, giving quite a few PSTN guys
sleepless nights.

Imagine this scenario – in my Ahmedabad office, I pick-up
a regular telephone handset and hear an actual US dial-tone, allowing me to call
any other US phone number as if it were a local call.  Then think about a
scenario where my


customer dials a regular US phone no. and the call rings right in my Ahmedabad
office, completely transparent to my customer, with neither one of us having to
bother worry about international long distance (ISD) charges. 

Taking this a step further, assume that I wanted to call a
number in


-I now have a choice between using my landline (at around Rs. 10 per minute)
or using VoIP (at around Rs. 1 per minute).  All I need to make all this
and much more possible, is a broadband connection (starting at Rs. 250 per
month) and a cheap (starting at Rs. 2500) VoIP adapter (and yes, no computer).

A VOIP adapter connected between your telephone and VSP is used to convert voice into data packets and vice-versa, that enables the international calls

I guess you now see what is causing sleepless nights to
those PSTN guys! This is first, in a series of articles on VoIP and addresses
the basic stuff-what is VoIP, how it works, usage scenarios and advantages,
what you need to get started, costs and legalities.

How it works
As the name suggests, it carries voice over Internet-which means you need
to have (a) an Internet connection, (b) voice adapter-a device/software that
allows converting voice to data-packets (so they can be transported over the
Internet), and (c) a VoIP Service Provider (VSP) that facilitates the transport
of such data packets to/from other VoIP or PSTN phone users.

Internet connection
An ‘always on’ broadband connection is a good start.  Around 64kbps
throughput (Upload and Download) is good for each VoIP ‘phone line.’ Most
broadband connections available these days are 128kbps or above-which would
suffice for a VoIP line as well as for other Internet requirements (browsing,
downloading, etc).

VoIP adapter
VoIP adapters primarily perform the function of converting voice to/from
data-packets.  On one end of this adapter is an audio interface while at
the other end is an Internet connection interface. Such adapters are available
in the form of software or as a hardware device.  The software, also known
as a ‘soft-phone,’ is something that needs to be installed and operated on a
computer. Soft-phones use the computer’s speakers and microphone as the audio
interface.  X-Ten Lite, offered free at is a comprehensive,
yet easy to use soft-phone. 

Hardware devices, also known as analog telephone adapters
(ATA) are standalone devices that allow for connecting most phones (using an
RJ-11 interface) for VoIP use-the phone is used as the audio interface and for
dialing phone calls.

Using a hardware device not only eliminates the need of a
computer (expensive) for VoIP, but also provides far better functionality
including better voice quality, ease-of-use and integration of VoIP with
existing phone systems (PBXs).  Sipura, now acquired by Linksys, has an
exhaustive range of next-generation VoIP adapters-in addition, most network
equipment vendors – Netgear, Linksys, D-Link etc, all offer VoIP adapters.

VoIP service provider 
A VSP is similar to a mobile operator – just as a mobile phone needs to
connect with a mobile operator, a VoIP adapter needs to connect with a VSP to be
able to make & receive calls.  VSPs operate and maintain the
infrastructure required to ‘carry’ VoIP call traffic and (similar to a
telephone exchange) allow for connecting to & from other VoIP or PSTN phones
& networks. 

Returning to our analogy of a mobile operator, choices for
selecting a mobile operator largely depend on geographic location – VSPs in
that sense are location specific.  Depending on individual calling
requirements, users can choose a VSP from across the globe.  VoIP being an
internet phenomenon, a user can choose a VSP from across the globe (more details
in the next part).  Upon registration each user is provided with a unique
VoIP ID, in most cases a numeric ID (also known as ‘virtual number,’ eg.
1234567) which is used for authorizing and connecting your VoIP adapter to the
VSP’s service. The virtual number combined with the VSP’s server address forms
yet another unique Id called an SIP address (looks very much like an email
address, eg.  The virtual number allows for
receiving incoming calls from other VoIP users of the same VSP.  The SIP
address goes a step further and allows for receiving incoming calls from other
VSPs and connected networks.  Some VSPs go to the extent of issuing a
regular PSTN number (also known as a DID, short for direct inward dialling) in
the form of country code + area code + phone number, eg. +1 (212) 5554321, which
can be configured to ring on your virtual number or SIP address.  VSPs also
offer a whole host of value-added services like call forwarding, voice mail box,
conferencing, call history and so on.

Outgoing calls
Upon successful connection, the VoIP adapter allows for making outgoing
calls — in a fashion similar to making a call using your existing (PSTN)
phone.  Pickup the phone handset, listen to the dial-tone and dial the
number you wish to call.  Drastically reduces the learning curve, doesn’t
it? In fact, there is no learning to be done! Outgoing calls can be to other
VoIP users using their virtual numbers (if from the same VSP) or their SIP

Given the early stage of this industry, and to drive
adoption, most VSPs offer free VoIP-to-VoIP calling.  VSPs also allow
outgoing calls to PSTN phones-just dial the country code, area code and phone
number.  Such calls are charged on a per minute basis and their rates vary
depending on the country, region, and whether the destination is a landline
phone or mobile. 

Most VSPs list their outgoing PSTN call rates on their
website.  Certain VSPs may be cheaper for certain destinations and
expensive for others-so compare the rates before you decide on a VSP. 
The good part is that (depending on your VoIP adapter) it is possible to work
with multiple VSPs and choose specific VSPs for specific destinations-so go
ahead and design a solution that is optimal for your calling needs.

A VSP is location specific, and you have the option of working with one or more VSPs and manage how calls are routed through them

Incoming calls
Upon successful connection, the VoIP adapter also allows you to receive
calls.  Signing-up with a VSP typically provides you with your unique
virtual number or SIP address-which can be used for receiving incoming calls
from other VoIP users.  To receive calls from PSTN phones, this

virtual number needs to be mapped to a PSTN DID number.  A user’s unique
PSTN DID works like a regular phone number- allowing for receiving incoming
calls on the VoIP line from any PSTN caller world-wide.

PSTN DIDs are provided by most VSPs for a fixed monthly
charge-and you may have the option to select DID for a specific country and/or
specific region within a country.  There are a few independent service
providers that offer free DIDs for US and


.  It is indeed possible to get a DID from an independent provider and map
it to your SIP address-making it possible to use a VSP in one country and
getting the DID from a service provider in another country.   

Most VSPs provide a choice for DIDs — allowing you to
choose a DID of a specific country or region within a country.Anyone can call
anyone irrespective of which voice network they are using.

Advantages of VoIP
The easiest way to understand the

advantages of VoIP is to think about what

e-mail did to postal service (snail mail)- cheap (if not free), faster more
reliable delivery, does away with notions of geography or distances (zip code,
state, country etc.), works anywhere you have internet connectivity. In its
native stage VoIP does way with the notion of country code + area code + local
number-a VoIP user is given an identify similar to an e-mail address viz
number@VoIP_service_ provider (eg 1234567 @ or 9876543 

VoIP allows you to roam with it, in another city , country   or even
when you are  airborne! (leading commercial airlines have already started
offering in-flight WiFi). All this works transparent for your callers as well as
for you-when receiving and making calls.

Like most Internet services, this one too won’t cost an arm and a leg. 
The choice for a VoIP adapter ranges from free softphones to entry level ATAs
(around Rs 5000) to high-end ATAs (around Rs. 10000). 

Similarly, VSPs come in multiple flavours- from an ‘all
free’ one to a ‘pay-per-use’ or a monthly subscription based one. 
Some VSPs even give away VoIP adapters if you commit to using their services for
a 12 month period.  Best of all, the ongoing usage costs associated with
making calls are at a bare minimum-call the VoIP enabled nations like US, UK,
EU, Australia, Singapore, Hong Kong and China (India to soon join this rank) for
as low as Rs 1.50 a minute.  Incoming calls-irrespective of your
location-are mostly free. 

You still end up paying for your Internet connectivity (one
place the PSTN guys can still continue earning a living out of-that is until
GoogleNet becomes all pervasive).

By this time you must have already gathered that it is possible (and highly

recommended) to design and implement a VoIP solution that is just right for your
calling needs.  VoIP gives you the flexibility to:

  • Choose between a hardware (stand alone) or software

  • Work with one or more VSPs and manage how and which
    calls are routed through them

  • Get one or more PSTN DIDs to receive

    ‘local calls’ from across the globe

  • Choose when and where calls should ring

  • Choose the level of audio compression, thus,
    controlling your bandwidth usage

  • Last but not the least, take it with you



of ambiguity around the legality of VoIP in


.  My understanding is that:

  • It’s OK to use VoIP through an authorised
    ISP-allowing for incoming and outgoing calls using any valid internet

  • VoIP needs to operate in its own space- cannot
    connect VoIP with our PSTN/Mobile network.

  • All this is set to change with the new telecom policy
    which comes into effect from January 2006.

In the next part
We’ll discuss setting up your own VoIP solution, service options and
associated costs, real-life VoIP usage scenarios,  and


‘s new VoIP policy.

Chirag Patel, CEO, Net4NUTS

No Comments so far

Jump into a conversation

No Comments Yet!

You can be the one to start a conversation.