1.1 What is VoIP?
VoIP stands for "Voice over Internet Protocol" and is simply
using your Internet connection to make and receive telephone calls rather
than going through wires via a Telephone Exchange in the traditional
manner.
1.2 Why would I want VoIP?
It costs much less than standard Telephone services, particularly if
you make a lot of Interstate and overseas calls*. As an example most
VoIP providers in Australia consider calls between most capital cities
as local (some even count these as untimed). My office makes lots of
these interstate calls and switching to VoIP has reduced my phone bill
by around 60%.
Also bear in mind if you regularly call the same numbers, most VoIP
providers do not charge for calls between users on the same service
so it can be worthwhile to encourage your regular contacts to join up
with the same provider.
*If you're not a heavy phone user or use it mainly for local calls and
calls to mobile phones then it may be difficult to justify the setup
costs of switching to VoIP even though you generally will still save
money on call charges.
1.3 What is the quality like?
Most of the time (better than 90%) you wouldn't pick it from a standard
phone line, but it's not always perfect. Sometimes you can experience
lag (slight time delay), dropouts or crackly sound as if you're talking
to someone on a mobile phone driving through tunnels etc, and occasionally
one party may have difficulty hearing the other.
1.4 How does it work?
A traditional phone converts sound to a electronic pulses via the microphone
which then go down a copper phone line to be reconverted back to sound
at the other end via the telephone speaker*. VoIP takes the process
a step further by converting the electronic pulses to computer data
which can then be sent over the Internet using the TCP/IP protocol and
then reconverted back to an electronic signal to the telephone. The
encoding and decoding process is performed using an algorithm called
a Codec.
A VoIP phone call can be done in two ways:
1. Call other PCs across the Internet directly by IP address. This can
be done with either a softphone or ATA and doesn't
necessarily require a VoIP service provider.
Advantages: free (apart from your ISP).
Disadvantages: You won't have a phone number, you can't make or receive
calls from regular land lines, and most home users have dynamic IP addresses
which change fairly regularly so it can be a bit of a pain finding your
contacts when you need them.
2. Exactly the same as you make a call now, even using the same phone
that you have now by using a device called an ATA
(Analogue Telephone Adapter) that links your telephone to your Broadband
Internet Connection.
* Quick trivia: To save on the amount of electronic signal that
has to go over the phone lines, all sound waves below 400 hertz and
above 3,400 hertz are removed which is why voices sound different over
the phone.
1.5 What do I need?
First of all you'll need a Broadband Internet connection. (While it
has been done over dial-up the results are usually pretty ordinary.)
Next, while you can make calls across the Internet connecting directly
by IP address (note: this requires technical knowledge & ability),
most people would want to be able to use their VoIP service to make
and receive calls to and from standard telephone numbers and use it
in exactly the same manner as a normal telephone service. To do that
you'll need a VoIP service provider.
Finally, you'll need a device to talk into and something to allow you
to hear the person on the other end:
1. Softphones: don't necessarily require a Router
and work using software on your PC and your PC's speakers and a microphone
or a USB Phone or Headset plugged into your PC.
2. ATAs (Analog Telephone Adapters): plug into a
Router equipped computer network* on one side and accept a standard
analog phone (like the one you're using already on your copper line)
on the other side. ATAs do not require a PC in order to function but
using a PC is usually the easiest way to configure them when they're
first plugged in.
3. IP phones: plug directly into your Router
equipped computer network* and can be thought of as a phone with an
ATA built-in. Like ATAs, IP Phones do not require a PC to be on.
4. Routers with an ATA built-in. These are the
cheapest option if you need a modem and/or Router as well.
* Many IP Phones and ATAs can work without a Router if they're plugged
into a modem connected to an ISP that uses a DHCP connection type like
Optus Cable. Mind you, this would mean nothing else would be able to
be plugged into it (like your PC) at the same time so I can't see that
option suiting too many people.
Some other ATAs and IP phones even have PPPoE clients to connect to
ADSL through a non-routing modem, but again, why bother when most ADSL
modems available now are Routers anyway.
1.6 Do I need a Router if I want to use VoIP?
It depends on what type of VoIP hardware you plan on using.
For softphones, if you just have one PC online and don't mind using
a microphone with the PC's speakers or a USB phone/headset then a router
is optional. However, if you'd like to use your existing phone (eg cordless)
then a Router with an ATA is the way to go.
If you plan on connecting to VoIP sooner or later then choosing a Router
with a built-in ATA up front will usually save a
few dollars over buying a separate ATA. But if you'd prefer to use a
separate ATA, for example to take advantage of a better feature set,
then I recommend choosing a Router with QoS
to get the best results. In most cases VoIP will work fine with just
about any Router but QoS provides the ability to give the VoIP traffic
priority so any downloads that might be occurring at the same time won't
interfere with the voice quality.
1.7 Do I need a special ISP to use
VoIP?
No, VoIP will work over any Internet connection that is
fast enough to carry the data (ie a Broadband connection). The only
thing to watch is some ISPs that might block some traffic on low
end ports that might be required by the VoIP protocols. That being
said I am not aware of any ISPs doing this at the time of writing and
since VoIP is a strong selling point for Broadband Internet connections
they'd be shooting themselves in the feet if they prevented it.
1.8 What if I want a PABX and VoIP?
My office uses an Engin SPA-2000 ATA with its two lines feeding into
an Analog PABX along with two standard copper lines so we have 4 lines
in all to make and receive calls from. Sweet and simple.
For a larger or more complex situation there's solutions like the Open
Source Asterisk
PABX which can be installed on a PC using hardware from Digium
for the physical interfaces.
Then there's ready made equipment to suit just about any size and application
such as that available from Vodtel.
1.9 How much does VoIP cost?
When looking at costs its important to consider the costs of getting
connected as well as the ongoing charges once you're up and running.
Getting connected:
1. If you're not on Broadband yet, your Broadband ISP might charge a
connection fee.
2. Signing up with a VoIP provider also usually draws
a connection fee of some sort which varies depending on whether there's
any included hardware.
3. Broadband Router and any VoIP hardware you would
like to use.
Ongoing charges.
Aside from your Broadband Internet connection you'll also have ongoing
charges with your VoIP provider. These are usually charged in a similar
style to Mobile Phone plans with a rate per call and/or plans that include
a certain amount of calls for a set rate per month.
For a quick cost comparison between Aussie VoIP providers see OzInternetPhones.
1.10 How much bandwidth does it require and/or
use?
Speed wise, I would generally recommended that a minimum of a 512/128
kbps connection is used for a single VoIP line. Any lower and the quality
can drop, particularly if downloading or surfing the web at the same
time. For more than one line, a good rule of thumb that I've found is
to allow around 128kbs upload per line. 128k works fine (using the light
G.729 codec) for one line but when two lines try to use it I find they
both start getting crackly with lots of dropouts*.
In terms of how much data is consumed per call there are quite a few
variables that make it difficult to gauge accurately. Different codecs
have different consumption rates, the length of calls vary and times
where you're not actually speaking means that there's no data to transfer.
For a very rough idea, one of the most popular codecs, G.729, has a
consumption rate of just 8kbps which would roughly make a one minute
phone call around 200 Kbytes once all the background traffic and so
on is factored in, which means you'd manage several thousand of these
theoretical one minute calls (or around 80 hours) to use one gigabyte
of data.
Newport Networks have
an excellent WhitePaper on this subject here.
*Note: I came to this conclusion while using a Sipura SPA-2000
on Telstra Cable which was capped at 128K upload and the problem went
away after switching to a 256K upload on an ADSL plan. However, I have
since learned that the SPA-2000 can only cope with one G.729 call at
a time. While they can be configured for both lines to use G.729, in
reality once the 2nd line is picked up it doesn't have the processing
power to cope with two G.729 calls at once so it will switch to a different
(and more bandwidth intensive) codec on that line. So, in reality it
just might be possible to get away with less than 128k per line
if you have an ATA that can cope with two or more simultaneous G.729
calls but without further testing I can't say that for sure at this
stage.
1.11 Will I get a new phone number?
Yes, if you sign up with a VoIP Service provider
you will get a new phone number.
If this will be somewhat of a disadvantage, choose a VoIP Router or
ATA with an FXO port that can receive calls from
both your old number and new VoIP number to the same handset.
2.1 What's a softphone?
A softphone doesn't necessarily require a Router and works using software
on your PC with either your PC's speakers and a microphone or a USB
Phone or Headset.
2.2 What's an ATA?
Analog Telephone Adapter. These plug into a Router equipped computer
network on one side and accept a standard analog phone on the other
side. ATAs do not require a PC to be on to function, although using
a PC is usually the easiest way to configure them when they're first
plugged in.
2.3 What is FXO?
Foreign Exchange Office. Looking at the phone cable that runs between
a phone socket and a phone, the FXO port is the one that the cable plugs
into on the phone itself.
Routers and ATAs that feature FXO ports allow your existing copper line
to access the same telephone handset so if the Internet is down or the
power is out it will "fail over" to the old copper line. Many
of these products will also allow an incoming call to either your copper
phone number or your new VoIP phone number to make the same telephone
handset ring.
2.4 What is FXS?
Foreign Exchange Subscriber. Using the same phone cable mentioned above
that runs between a phone socket and a phone, the FXS port is the wall
socket. On a Router or ATA, the FXS port is the new "wall socket"
that you'll be plugging your phone into.
2.5 What is SIP?
Session Initiation Protocol. A protocol that links phone numbers to
IP addresses which allows VoIP users to call and receive calls using
just phone numbers.
2.6 What's a Codec?
Codec is short for Encode/Decode and is what is needed to convert sound
to electronic data and back again so voice can be sent and received
across the Internet.
