Let’s see if SIP Essentials is a good fit for your training requirements. In this five day class will take a look at the SIP protocol. We will take a detailed look at the Grand picture all the components how they all fit together there’s lots of labs, lots or graphics to make the picture clear. Each chapter will follow this format: we will begin with the vocabulary that will use this vocabulary is probably not necessarily part of your vocabulary so we’ll make sure that we’re not using any terms that you would not be familiar. We also define them straight up at the beginning of each chapter. There’s lots of pictures and diagrams that will describe the concepts were not big in the text lives like this one we actually like to use diagrams of things. We always focus on the big picture before we do that deep dive into the protocol we want to make sure you understand how the protocols going to fit into your environment into any environment for that matter. There’s lots of labs and the labs are directly applied to the topics that we are covering furthermore using all freeware so you can replicate these labs at home or at your lab at work. You can also use them to test interoperability in all kinds of possibilities as you may decide when you choose to actually put that in production, at least for testing.
We always finish each section with review questions. Now chapter one basically focuses on everything we cover all the topics in this one chapter that the whole course for ultimately provide. We want to make sure that you possess the Grand picture about all the components are going to fit together. This is the time to make sure, that if you’re comfortable with the voice side. But the data side is new to you. We make sure that that’s understood if telecommunications a somewhat foreign to you. We’re gonna speak both your languages in this chapter and make sure there’s a understanding upheld. Voice over IP functions, particularly under the control of Session Initiation Protocol (SIP). Our emphasis is always on concept proper use a vocabulary we identify all the boxes when we’re finished you’re going to clearly understand the big picture. Let me show you an example of one of those slides that we actually see in the first chapter.
Now, this is one of many that we use to describe interoperability this is an example of a SIP call setup that’s interoperating into the public switched telephone network. Let me explain this one just like I would if we were in class. The call setup is going to be hopping across this path, where this portion, at least that far, is going to be public switched telephone network. The remainder up the signaling path is going to be SIP.
We’ll talk about the interoperation right here. This is where the magic is going to occur so our originating party goes off hook, we have thirty milliamps of current flowing and our user dials this phone number you see over here on the right so after that dot the digit 9 215 555 1978 is dialed, a setup messages sent from the PBX to the end office. Now the setup message contains the calling party’s number, the called party’s number and also the channel that the caller is on. Now that the end office knows this information it must make an autonomous decision based on this information the decision that it makes is part of its routing table known as the dial plan it has its owned. I’ll play at it did not learn the DOL, planned from telephone switches there adjacent to it like you would in an IP network for OSPF or up he IGRP. Some other interior gateway routing protocol would have told that this is not the case in this particular case a human being has to tell this which how to route calls and the entry then made as a static routing table in this particular case. Let’s say that are and office chooses this as the best path that it has two hundred in a machine trucks choose from let’s assume that none of those trucks are busy right now.
Well, our and office was provisioned to know that signaling system 7 point code 3.5 point. I’m is how to talk to our next tandem switch so an initial address messages sent the initial address message specified is going to destination 3.5 point, nine from the originating point code 3.5 point to a signal transfer point, which looks more like a router really that telephone device. Simply responded to the destination point good 3.5.9 and relayed initial address message to our tandem switch. Because it too is configured with a static routing table but this time the static routing tables for point codes. It’s not for telephone numbers so now are called telephone switch the third one in a row have now knows the originating party’s number the terminating party’s number at also does the call is on channel identification code 19, it must make a routing decision based on its doll play at and its decision is to send that initial address message to our next telephone switch. Well to our 10 a.m. switch it thinks the next telephone switch is a PSTN or public switched telephone network TVM switch and using signaling system 7 the message is sent to 3.5.3 and now our first switch the begins the voice over IP network knows the originating party’s number the terminating party’s number and it knows the calls on channel identification code 22 now. It’s time to talk about these little termination points this little termination points are known as a termination specifically these are physical terminations and their patch together with a a logical or a digital.
Pat scored so that these two terminations interconnect in a context. So, we’ll have a context-free here they’ll be a context in the PBX and in fact right now we have three and a half of them but we begin these Sep networking now the Session Initiation Protocol invite is set first from our tandems which is really what this red this yellow switches to a back to back user-agent: this would be a feature server that happens to know the whereabouts a bar called number because prior to this this end-user registered so the IP address or the demesne over destination is known by the future server the feature server simply relays the SIP invite to where the registration came from now a session border controllers gonna make modifications to the invite making it appears though the invite originated from the outside of the session border controller what you should know is that a session border controller has two interfaces one facing in which usually has a private address one facing out which has a public address.