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If you hate long posts as I always suggest go through this video lesson (click here) Now, we already know that in real SIP world, any UA when it wants to communicate with another UA should take the help of “SIP Proxy Server” - which finds the actual location. Because it is not practically possible to remember all other UA’s addresses. All good till now. The next question which comes to mind is How a Proxy Server able to find contact  address of an User Agent(Called Party). Here, Proxy Server takes help of “Location Service”. Location Server Location Service helps in providing the exact location of UA. Location server is a server which records and maintain the contact information of each and every UA with in a typical enterprise. Location Server has its own database, which keeps up-to-date info of each UA by another Service called “Registration Service”. The Server which provides this service  called as a “Registrar Service”. Registrar Server This Server
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If you hate long posts as I always suggest go through this video lesson (click here) Hello everyone!  Today we are going to deal with topic “SIP Addressing”. I have talked about it a bit in the earlier post i.e. SIP PROXY SERVER. SIP Address An address which identifies an user, a device or a service. SIP addresses are represented in the form of URI [Uniform Resource Identifier]. It exactly looks like our email address. SIP uses a number of URIs. Common URIs are shown below user@host     where,         user = it can be a name (or) telephone number             host = Domain Name (or) IP Address Eg:             sip:+914022222222@                   sip:rajeshkumart@                sips:rajeshkumart@ For SIP, the URI scheme is either sip for a normal SIP URI or sips for


Thanks everyone for the amazing response on the blog ! In the last post, we discussed SIP SYSTEM ARCHITECTURE. Now, I hope you know “ understanding SIP” means not just knowing about Protocol. Every component mentioned in the architecture plays a vital role of its own. I have already reveal the secret of each component what it does. Now, in this post and further, we will be dealing each component a bit deeper. So, today's component is Proxy Server. RFC 3261 says: SIP proxies are elements that route SIP requests to user agent servers and SIP responses to user agent clients.  A request may traverse several proxies on its way to a UAS.  Each will make routing decisions, modifying the request before forwarding it to the next element.  Responses will route through the same set of proxies traversed by the request in the reverse order. Why do we need it? The actual question should be why do we need a proxy server if two UAs able to communicate each other dire


Today's blog is all about "words of life". If you know the difference of understanding these words, then I surely can say that you can make the difference. You can make the difference, if you start seeing them different. Enough of saying 'differences' , let me take you to the actual content what I would like to take you through. Before we enter the post....What is this topic about? Why am I posting this?  Allow me to explain. Understand this, out of this telecom world, I am a common man who always wish to Make The Difference wherever I am interested in. The way we have grown, in our childhood and then later, makes lot of impressions in our mind and becomes "belief" while time flies.  At times you see these impressions, instead I'd call them beliefs, limit them knowingly or unknowingly. Every person in the world come  across  them. So, I am also a person with lot of beliefs. We can call these beliefs (or) principles as "Tenets&qu


Below is the video where I have demonstrated how exactly a Peer-to-Peer SIP Call looks like. I also emphasized enough glossary which helps in understanding the basic SIP call flow. Hope this helps! Please provide your comments if any. Thanks, Raj


As a part of Learning SIP, in the last post I did demonstrate on a Basic Call Flow of SIP. Today, I am going to take you through the SIP System Architecture. SIP is a revolution in this modern world of communications. Rather I would say that SIP alone did not bring this change. That's where I would like to introduce SIP SYSTEM ARCHITECTURE. Each component of this architecture has contributed and made this drastic change in Telecom World. So, why wait! Lets go through the architecture and its components. SIP System Architecture SIP Endpoints: SIP Phones, SIP Soft clients running on PCs, mobiles etc. Proxy: This server accepts INVITE from any SIP endpoints and process the request. This is the server which decides whether the call need to terminated on to another SIP Endpoints (or) to another PBX (or) to PSTN. The routing decision would be taken by the logic written by Administration of this proxy server. It is purely for Session Management.