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IP Telephony VOIP – realy basic explanation

I am IT engineer and I work also in IP telephony. I decide to write this article based on experience from the field where users asks me, why I replace old phones and what  will be advantage on new IP phones.  I find the explanation of SIP or H.3232 technology is very difficult to understand, especially for people over 50’s and I decide to find a way to explain that could understand anybody.

At the beginning a little history about telephony
We are familiar with telephones from long time ago, exactly from year 1870. The first inventor Alexander Graham Bell designed devices that could transmit speech electrically (the telephone).
In the mean time till today happened a lot of new things on the telephones.  After the invention of mobile phones we thought nothing new could be invented.

But, there is always something that we can make better. If not better it could be cheaper. And IP telephony (VOIP – Voice over IP protocol) can make calls very cheap in some ways also free of charge. And what is the difference at IP telephony vs. »classical -PSTN« telephony? We don’t need to connect our phones to special outlet and service provider  don’t need to place additional wire to our apartment. We can use pair of wire or much better fiber optic connection for telephony, TV and internet connection. This is view from user site, but if we are looking from provider site, we can see big difference in technology.

Now we find what is media used for IP telephony ( VOIP – Voice over IP protocol) and the next question if we already have internet connection is what IP telephone to buy.  Do we really need new telephone or we can use old one?  I believe that everybody wants new phone, because people likes new things.  But there are still a few people who like their old phones. Inventors find solutions for them too, which is called media converters.  Media converters convert our voice from analog signal to digital and this one is converted to IP world. The box where we connect old phone on one site and the internet on the other site we call media gateway.  Simple!!! Not really, but in this article we will not explain in details how technology works. It is important that you understand basics.  IP telephone we can connect directly to the internet and it should work. And here is first advantage. If you travel to different places around the world, you can take your phone with you. Practical? No of course not. But most people today travel with notebooks and notebooks are usually connected to internet. Another solution and advantage of IP telephony (VOIP – Voice over IP protocol) is soft phones. This is software installed on your system and this software act like phone. Another good thing is that we can find on the internet software for free. Software for free, calls almost  for free( like you call from own country) , you can forward your calls also to mailbox… everything one big advantage.
Now, let we say that we decide to buy new phone. We can find a lot of producers of IP telephones and my experience  is that we have to search to find bad quality telephone. It is important to buy right IP telephone, because they use different technologies. But your provider will tell you what to buy if you ask them. Oh, and I almost forgot to tell you. Most of providers give IP phone for free.
If you are interested please research our site and find why to search another IP phone.

Term – VOIP Voice Over IP explanation
VoIP (or IP Telephony, Internet Telephony, DSL Telephony) is a used term for the technology that use the Internet Protocol to exchange voice and other communication services. So far this services mainly have been carried over the public switched telephone network (PSTN)

If you think you get usefull information you can :

Session Border Controller – SBC

I believe you already hear about  Session Border Controller  named  with acronims SBC . I will try to explain in short what is main purpose for this box. We can see from name this is the box which controll something between border. And what could be the border or better if we ask where is this border. We talk about Networks border and Session Border Controller is box which separate LAN (Local Area Network) and WAN (Wide Area Network) in IP telephony world. If we don’t know much about IP telephony we can say this is some kind of firewall fro IP telephony. SBCs are inserted into the signaling or media paths between calling and called parties in a VoIP call. Of course they using the Session Initiation Protocol (SIP), H.323, and MGCP call-signaling protocols.

In many cases, in order to hide the network topology and protect the service provider or enterprise packet network, the SBC will terminate a received call and initiate a second call leg to the destination party. In technical terms, when used within the SIP protocol, this is defined as being a back-to-back user agent (B2BUA). The effect of this behavior is that not only the signaling traffic, but also the media traffic  can be controlled with Session Border Controller  –  SBC. In cases where the SBC does not have the capability to provide media services on board, SBCs are also able to redirect media traffic to a different element elsewhere in the network, for recording, generation of music-on-hold, or other purposes. Conversely, without an SBC, the media traffic travels directly between the VoIP phones, without the in-network call signaling elements having control over their path.

Additionally, some SBCs  allows VoIP calls to be set up between two phones using different VoIP signaling protocols (e.g., SIP, H.323, Megaco/MGCP) as well as performing transcoding of the media stream when different codecs are in use (e.g., from g.722 to g711)

OK, now we know that SBC hiding “inside” network topology from outside world,  and this is very good if seen from the point of view  for network security.

Don’t Start From Zero For an IP PBX Exchange

Most of us prefer either to buy a ready made VoIP solution or build a new one from scratch. To me, both of these approaches are wrong. Starting from scratch is just like making a new car that suits your CD player. Definitely, the right approach would be to do a few changes in a car that was purchased from market.

The point is if you need to build a small exchange, don’t start from zero. Just buy a reliable solution from any VoIP provider and customize it with IP PBX. Purchasing a solution that can be modified later, demands some expertise and intelligence. Remember, a solution from a particular provider may work for one situation but it may not work at all for another. In my case, Axvoice.com has worked most of times. All plans from Axvoice offer up to 30 free features. That huge number of features makes Axvoice fit for most of the situations. Before you reach a conclusion, you had better get a clear picture of your desired output first and then select an Asterisk solution for your IP PBX.

To cut the story short, I would say, grabbing a solution from market and then changing it, saves a lot of time and money. For this purpose, asterisk is used on back end and PBX on front end. With asterisk, you can program your own features and other call settings. PBX provides you a GUI based interface to connect your soft phones. Another advantage of PBX is it provides free calls within an office or home. If you have already purchased an asterisk and PBX compatible solution from a provider, you will be able to complete your task quickly.


One of advantages of IP telephony is also presence. Why to call somebody if you already know that this person is out of office. Waste of time and we all know the time is money.  I already mentioned I am familiar with Siemens products and they made beautifull features which is part of Open Office PBX.  One of them is myPortal.

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Conference call

What is the exactly conference call? I will try to explain on simple example. Mrs. Maria calls her husband Mr. John and she ask him when he hav time to go to the shopping. After shopping they go to the lunch with family.  Now Mr. John will take younger daughter but he doesn’t know when she will finish with gymnastic. After all they also have coordinated with older soon.

One solution but not so good is that somebody calls all participants and coordinates right time for launch.  Much easier in this scenario will be if Mrs. Maria establish another call with soon and Mr. John with his daughter but they stay in connection with each other. Now we have conference call involved four people. They can all hear each other and they can coordinate t right time for launch -easy and fast.

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SIEMENS OpenStage 15 SIP

We already met the top of the SIP phone from Siemens OpenStage (OpenStage 80) family  which is of course also most expensive. In this article I will introduce OpenSatge 15 the “smallest”  SIP phone form OpenStage family. Why is interesting ? On the first place is price but I will not tell you what is exactly price because you can find it at local dealer. I can tell you the price is low regarding performace you get with this phone.

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How to connect phone and PC on same cable

I know this explanation will be a little more than really basic but it is important to know how things work. If you will look on back side of your SIP telephone (or any IP telephone) you will see two 8pin connectors (most phones have) which are the same. This is RJ45 connectors and ere you will connect your IP telephone to the internet. But why two? Double internet connection maybe for backup if you cut one …no of course not.   There are two connectors and one is for connection to internet and the other is for your PC.Let we suppose we have advanced ISP or own local area network in we have separated telephony from other data with VLAN’s. Now this will not work if you don’t have switch who know to work with VLAN’s. Now, what is VLAN’s ? Too much for detailed explanation but you can imagine that your internet cable connected to the phone have two more “separated – virtual” cables with different data inside. One for phone data and other for PC data. I hope you understand. So if you have that kind of switch and switch is configured as should be then you can connect your PC to your phone and this should work.

X-lite SIP soft phone tutorial

X-lite,SIP application for making phone calls. It is very easy and completely free and we are going to look now how to install and configure. First of all you have to go to the website www.counterpath.com .This is the company that makes x-lite. Find link for download x-lite free. You can chose between free and payable version. For testing you can begin with free version. Of course you can choose download for your platform (windows, Linux, Mac). So after download finish you can start with installation. You can start and and let all to default. Once you have it installed and loaded up you can see the face of X-lite. You don’t have enabled SIP account yet. Now chose upper left button (down arrow) and enter SIP Account settings. As you can see there are no SIP accounts yet. So we were going to add new account. Press Add. Now you have to know your account setting (Display name, User name and Authorization name) just insert data. Uncheck domain proxy and press Apply, then go OK.

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OpenStage 80 SIP phone from Siemens

Regarding I am familiar with Siemens products I will show you some of them. I will start with best and here you can see description for OpenStage 80. Impressed, that is first what I can say about this telephone. It is really a little expensive but worth this money.

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IP telephony and securitiy

The question about security is always in front of everything. However if you are worried that somebody can listen your phone conversation……I really don’t know what is good answer. Of course everything is possible especially if you don’t know what you are doing, for example if you have your soft phone on your laptop and you are connected to wireless router without password for connection. If you have somebody in your company and he is familiar how to connect between your phone and switch or how to make port mirror on switch and capture data. Listening somebody on IP telephony is possible. But I really don’t understand why some people are so worried. In times of analog telephony was listening
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Why telephony – I have skype ?

If you read About me, you can see that I work with customers on the field. I hear a lot of questions, how, why, is that necessary…….and one of them was also why stand alone or soft phone telephony if I have Skype? Yes, it is maybe true but believe me this guy who ask this question was not over 30 years old. Younger people grown up with telecommunications inventions and they are faster with learning new. Tell to my 60 years old mom she must call me over the Skype. I think that will never happen. It was already hard to introduce new cell phone and working with.
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