Sunday, February 26, 2006

VoIP Demystified

It’s almost impossible these days to browse internet or watch TV and not to hear at least one of the following words: VoIP, Skype, Vonage, Lingo. Most people perceive them as alternative ways to make cheap phone calls which is no far from the truth, but for the majority of IT people this statement is not enough. If you are one of those persons that constantly read IT news and blogs about new technologies and gadgets then probably you’ll want to learn more about the technology behind this so popular VoIP concept.

IM times

The majority of you tried at a certain point in time one or other instant messenger program like: ICQ ( ), MSN/Windows Messenger ( ), Yahoo Messenger ( ) or AIM ( ). They all tend to have the same type of user interface that allows adding friends in your list and monitoring their online status. Then the software facilitates communication with either of them via exchanging text messages typed in real time. The competition in this software area determined producers of instant messengers to add more and more functionality besides text communication such as audio and video communication. Because of the fact that computers usually sit behind a NAT or firewall that without proper configuration block certain type of communication and because the audio features of these programs were added as bonus to instant text messaging a limited number of users used these features.

Here it come Skype.

Skype ( ) was developed since the beginning as a PC application having its primary function audio communication. Its user interface resembling a typical IM program and the secondary function of instant text messaging appealed to many heavy IM users. The technology used for audio communications based on the same principle as peer-to-peer networks made others to believe that this may be the solution that brings Skype an advantage that the other IM applications doesn’t have it. In the end the good audio quality definitely promoted Skype as a leader in PC to PC voice communications. Other than this nothing counts for the home user to whom Skype addresses. The typical user is not interested in standards and doesn’t always mind how the application achieves its goal as long as the application looks cool and he is obtaining the wanted results.

The raise of broadband Internet

Not long after a significant percent of homes started to have broadband Internet connection everybody noted the apparition of some new commercials that promote cheap telephony plans with more services than the standard telephone plan offered by local phone companies. Probably you remember those Vonage ( ) commercials. As opposed to Skype who targeted PC users these companies address their products to residential users without any computer knowledge. As a matter of fact you don’t need to be a computer expert to make a phone call to order a pizza or call a cab. To avoid the usage of PC to make phone calls using a broadband connection all these companies offers end users a telephone adapter that sits between the internet connection and a regular telephone. You, as end user are shielded from the technical aspects of this service: you receive a regular local phone number which friends can use it to call you and you can make local and long distance calls from you old telephone. What can be simpler than that? The only things that you’ll notice are lower monthly bills and sometime less than average audio quality.

What to use on the go?

Although is possible to take your telephone adapter with you when you go in vacation and use the hotel internet connection to make cheap phone calls that will appear on your monthly bill, the majority of mobile users use Skype (or other PC to PC communication software) when they are in vacation and use the VoIP provider only at home. This is because at least 2 factors:

Although the service offered by the residential VoIP provider is in fact more related to computers (or internet communications), than with the classical telephony, they promote the service as a replacement plan for regular phone service. Because of this, end users associate that service with a regular fixed line phone that you cannot take it with you in vacation. In reality this is a very wrong perception! Your VoIP plan (through Vonage for instance) is not much too much different than you’re Skype or Yahoo Messenger account. All you need to have is an internet connection and you have you’re service with you! The connection doesn’t have to be at your home!

The second factor that determines residential users to leave their VoIP provider plan at home and chose Skype while on the go is due to the inconvenience of carrying around the analog telephone adapter (ATA). As I said earlier the residential VoIP plan is more close to computers than to analog telephones so it makes sense to have some sort of software (similar to Skype) that you can install on your laptop and make phone calls charged by the VoIP provider. As a matter of fact this software exists and is called a softphone but the problem is that not all VoIP providers support it and some of those who has it charge you supplementary for such a service.

Knowing this, the decision of using one or other VoIP service while on the go may be clearer. Still they are some things in this article that may change your mind once more. Just have patience and read the rest.

What about the others?

At this point you may think that either Skype or your VoIP provider is the solution of VoIP communications. Still you have some friends that uses obscure services provided by companies such as SIPPhone ( ), FWD ( ), DialPad ( ), etc. and you are wondering why they are pocking around with those not so standard and known services and they don’t go with the standard?

The answer is simple: because those companies are THE STANDARD! How shocking or true is this statement you may find in the next paragraphs.

SIP World

Voice communication is the most powerful way of human communication especially when parties are separated by a long distance. Telephony is the technical infrastructure which makes possible the transmission of voice over long distances. Telephony with all its forms classical, mobile, VoIP, is one of fasted adopted and appreciated technology in human history. Until the crowning of Internet as the most complex interconnected system ever built the telephony systems had that place.

I hope you didn’t believe that such an important topic as VoIP which promotes cheap telephony on top of Internet infrastructure escaped researchers and standardization institutes?

VoIP subjects were in research labs and long before Skype appeared in this world. As this article is not a technical one, I’ll not insist on the multitude of standards and industry terms around this concept with one small exception: SIP which stands for Session Initiation Protocol.

SIP is a signaling protocol developed for a multitude of multimedia application ranging from games, virtual reality to voice and video communications. It is one of the leading protocols for Voice over IP communications. As the name states it is used only for signaling and not transporting media streams. Other mechanisms such as RTP are used for carrying audio data.

Suddenly in a so divided world full of services and applications that offers you free or cheap audio calls SIP comes to unite them under the same umbrella. Doing a quick research on Internet on the technology used by the majority of services that offer telephony calls using VoIP technology (including here residential providers and other sites on Internet) reveals the fact that almost of them are using SIP technology.

With the exception on Skype and other few applications that will not be mentioned here from this point on you’ll see SIP everywhere. For instance, I was not able to find even one residential VoIP provider that is not SIP based. Companies such as Vonage, Lingo, SIPPhone that once looked so different looks now much more alike.

Even they are following the same standards and protocols from commercial reasons they are hiding this to end users. They build SIP networks that theoretically can exchange data between them but actually they are not promoting inter-network communications.

Actually these networks are able to exchange messages but usually through the telephony systems and not always in a direct way. This raises the price of phone calls. Imagine 2 email systems (let’s say Yahoo Mail and Hotmail) allowing sending messages only in their network and all messages sent from one to the other being charged!

Audio quality

The audio quality in VoIP depends on many factors, one of the most important one being the codecs used to encode or decode voice messages. These codecs are much like the codecs used to encode/decode mp3 files but are optimized for voice encoding. Some of these are optimized for narrow band other for wide band. Some popular codecs include: G.723, G.729, G.711, G.726, G.722.

Besides these codecs the systems for VoIP uses also other technologies for noise reduction, echo cancellation, etc. in order to improve the quality of the phone call.

Codecs are the principal factor which makes Skype sound so good. They are using some codecs from Global IP Sound ( ) a well known company in VoIP arena. Other products as well are using codecs from Global IP Sound. One of the other products is Gizmo Project which will be presented later in this article.

DIY VoIP plan.

VoIP is cheap. But how cheap can be? For majority of users who just need telephone line simplicity is everything. The entire process is as simple as ordering a VoIP package from a provider and that’s it. They give you a telephone adapter, a local number and a call-out plan to call other people. From that moment you are all set and they start sending you bills.

Majority of these companies address to residential users who want to replace their regular phone plan with a VoIP plan to cut out the costs and receive more features in about the same amount of money they were used to pay for a local service. The low costs are also due to the fact that the Federal Communications Commission (FCC) doesn’t regulate VoIP like telephone communications.

For majority of residential homes a telephony plan consists basically in:

a real phone number used by other persons to call you;
a certain number of minutes / or unlimited to call other telephone numbers;
a device to allow usage of the VoIP provider without the need of a computer.

If you don’t have a telephony plan yet or you want to replace it altogether or simply your time is more valuable in other areas than I recommend you to go with a major VoIP residential plan such as Vonage ( ), Lingo ( ), AT&T CallVantage ( ), Packet8 ( ), SunRocket ( ), etc. which offers complete packages.

Make yourself a little research before decide which to choose. I recently noted NetZero ( ) offers a VoIP package starting at under $4 per month.

If you already have a plan with your phone company that you’ll just want keep it but you want also to foray into VoIP area and eventually use VoIP for cheaper long distance or international calls, than the next paragraphs are for you.

DIY VoIP plan.
It’s time to choose.

Should I use Skype? This may be the first question that comes into mind under this situation. As you know Skype offers free PC to PC communication inside their network but they have also other services at a certain cost. They allow you to buy Skype-Out minutes to call real phone numbers and they also have in beta stage a new product to allow buying of a Skype-In number that persons without a computer may be able to use it to call you.

What they don’t have is a device to allow usage of Skype without a computer. It’s true that they are plenty of USB based headsets and headphones available for Skype but all of them require a PC or at least a smaller device like a PDA. Since eBay ( ) acquired Skype we saw a more aggressive advertisement campaign around Skype so it’s possible that soon will appear some devices that will allow you to use the Skype network without a computer. Netgear ( ) announced such device.

Even if these devices will appear is still a far in the future till Skype will be accepted in a corporate environment. This is mostly because of its proprietary protocol that is not trusted by system administrators. Also the P2P nature of Skype which allow conversations of other users to pass through computer may not be appealing to some persons.

As opposed to Skype, SIP protocols are very well accepted in both corporate and residential environments. This may mean nothing to home users but the fact that it’s an explosion of cheap devices which allows connecting to SIP networks without the use of a computer should not pass unnoticed.

Believe it or not there are also SIP networks which allow you to sign up for free. All of them offers you free in-network calling and they just charge you for call-out minutes or for an incoming phone number (just like Skype). Combine this with the advantage that you can use both a software client (called a softphone), or a classical phone (without the use of a computer) and you may just discovered a very advantageous offer.

There are tens of SIP networks out there on Internet happy to open you a free account. Most of them include basic features such as free in-network communication, voice mail while other features such as call-out or incoming number may cost you. Some of them give you extra things upon opening the account, such as some free credit to test call-out features.

Since opening an account with these networks is free I let you discover as many as you can. It will cost you nothing. It still worth mentioning 2 free SIP networks that captivated my attention: SIPPhone ( ) and FWD ( ).

Interesting enough I find out also that some PC-to-PC VoIP providers that don’t mention on their site anything are still SIP based. VoIPStunt ( ) which offer at this moment free PC-to-Phone calls to US and other countries is also SIP based. You can use it with its own locked client or you may search on the Internet for information of how to use it with any generic SIP compliant phone.

DIY VoIP plan.
Necessary software.

OK. That’s good till now: I have an account with SIPPhone (or any other network) but what software to use? Skype is giving me a free application that I’ll install it in order to use their network, while SIPPhone is not giving me a client like this.

As a meter of fact is better that those SIP networks don’t offer you any client application. And you know why? That is because you can use any SIP compliant softphone (like the ones produces by Counterpath) to make and answer phone calls. Is like when you are using the same web browser even if you are visiting Yahoo or Microsoft or your own web site. Imagine Yahoo offering their browser that you can use to access only their non-standard site!

Counterpath, formerly Xten ( ) makes very good SIP compliant softphone. Its user interface resembles a touch tone phone. Although in my opinion this type of interface is not really what I what from a softphone the software qualities makes it a winner.

You may register the same SIP client with many networks to allow doing phone calls through the network that offers the best calling rate for the destination you intend to call. For instance I registered my X-Lite softphone from CounterPath with 2 SIP providers: one that I’m using to do cheap calls in the continental US and one that I’m using to do cheap international calls with a particular country. Choosing between the 2 providers is as easy as typing #1xxxx or #2xxxx where xxxx is the phone number and the first 2 digits allow selection of the provider.

It worth mentioning here a remarkable SIP client that tries to mimic Skype interface bringing also additional functionality such as call recording. Its name is Gizmo Project ( ) and as Skype offers an excellent audio quality mostly due to the codes from Global IP Sound. Unfortunately Gizmo Project is locked into SIPPhone network thus is not possible to register it with other network. Although is locked in a particular network this is not as bad as may appear. SIPPhone network is a very good one and because of its standard base nature GizmoProject allows to make free calls not only to people having other instance of GizmoProject but also to people without computer that have their telephone adapters registered with SIPPhone. Some may find the other features of GizmoProject such as free answering machine, free recording capabilities as very important.

A nice surprise is also Windows Messenger (not MSN Messenger) which offers SIP interconnectivity. But because of it’s limited capabilities it restraint me from recommended as a SIP softphone.

DIY VoIP plan.
Necessary hardware.

Unless you want to use the chosen SIP network only with a softphone is time to buy some new hardware. Fortunately the offer is vast in terms of available products and price ranges. A good starting place may be the online retailer ( ). Look there for the main two categories IP Phones and VoIP Analog Adapters.

You’ll be pleasant surprised by the existing offer. You can buy from there (or any other retailer) all sorts of adapters or IP Phones. Deciding between an IP Phone and an analog adapter (ATA) is based on your needs:
An IP phone looks like a regular phone the only difference is the input. Instead of the regular phone like input you’ll now find an Ethernet connector so you can plug directly the phone in your network. There are many types of IP Phones some designed for home use others for corporate use. Some requiring an Ethernet connection other are wireless.
An ATA device allows you to reuse your existing phone for doing VoIP calls. This is also what majority of VoIP providers offer you. By connecting a cordless telephone to the ATA device you can do wireless VoIP calls as well. An ATA has basically one Ethernet input and one analog telephone output.

Some adapters have also some nice to have features such as an extra phone line input so you plug an analog line and be able to use your telephone even if the VoIP connection or power are down. Sipura SPA-3000 adapter has also an FXO port allowing the device to behave like a gateway between the VoIP network and a landline network. For instance having this adapter at home you are able to make cheap international phone calls from your mobile phone by calling home and then the device you route your call to the VoIP network. It is also possible to forward the calls that come from the VoIP connection to your mobile phone.

If you are a beginner in this area I recommend you to go with an entry level device such as an IP Phone like Grandstream Budgetone 101 or an ATA device like Linksys - Sipura SPA-1001. You can order any of them online from .

Warning: If you’ll visit a local computer store such as BestBuy or CompUSA you’ll discover also some VoIP devices: ATA devices or even routers with built-in telephone adapters. Please read carefully the labels on the box since the majority of these devices are locked with a VoIP provider such as Vonage or SunRocket. Don’t buy those devices unless you want to subscribe with respective provider.

Other considerations

The quality of a VoIP phone call is dependent on the available bandwidth. If you are doing heavy downloads while you are on the phone you may experience a deterioration in audio quality. Here come into scene Quality of Service (QoS). If your IP Phone or ATA device is placed after your home router make sure the router has QoS features. Older routers usually don’t have this feature. Having or not QoS is the difference between a chopped conversation and a good one. Skype cannot benefit from the QoS features but traditional SIP phones can.

DIY VoIP plan.
Concrete scenario.

Q: I live in South Florida and I have Bellsouth ( ) as my local phone company. I have a local phone plan and ADSL bundle with them and I’d like to make cheap long distance phone calls using VoIP.

A: The easiest way is to make an account with SIPPhone and buy from them SIP minutes (you can call as low as 2cents / min in US). Then you can buy one ATA eventually having an analog input also for connecting your phone line to be able to do PSTN and SIP calls on one standard phone.

Actually SIPPhone is not the only service that allows you this DIY type approach. There are plenty of services out there which addresses to DIY type people. Just try to search on Google ( ) for “DIY VoIP” or “BYOD VoIP” and you’ll see what I’m talking about.

Your own internal phone system

Do you have a big house or a small business? Do you want that each room to have its own phone number interior like those phones from big corporates? If so, or even if you want to dig deeper into VoIP subject than its time to install Asterisk or Asterisk@Home (, ).

It is free and offers you with features found in systems that costs thousands of dollars. Search on internet for Asterisk and you’ll find all sorts of tutorials and documentations. You’ll find stories of people who installed Asterisk in virtual machines, just to play around with it, or people who install it in their basement, built embedded devices containing Asterisk and even people that are using Asterisk in a production environment.

What about video-calls?

Video calls are on the rise. Skype offer them as well as some SIP networks. The nice thing with video calls in SIP networks is the fact that you can find devices that allows to perform this type of calls without the use of a computer. Buy your grandma a videophone from voipsupply or any other retailer and she’ll be able to see it even without a computer.

Disclaimer and further reading

This article was written as a non-technical introduction to VoIP technologies. All companies, products and services mentioned are just for the purpose of exemplification. Users are invited to consult respective companies’ official web sites for up to date information about their products and offers. The author or this article is not affiliated with any of above mentioned companies.


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