VoIP and the Differences Between Analog and Digital Signaling

0:00[MUSIC PLAYING] So in this go, we kick it off by welcoming you to the course. We'll have a discussion about Cisco certifications in the event you want to go down that path. We'll talk about the impact of VoIP today. And also, we'll look at analog and digital signaling, see how they operate, and see the differences between both. So I thank you for taking the journey with me, and I'll see you in the next video.

0:00[AUDIO LOGO] Hello, and welcome. My name is Lalo. And I'm a trainer here at CBT Nuggets. And I wanted to start off this series to let you know what to expect from this course, but also discuss who exactly this course is for. Maybe you're new to Cisco Voice. Maybe you took a role with a different team within your company. Or maybe you start a new job, where you are a part of the voice team. Or maybe you're starting your journey pursuing Cisco certifications, but notice that most of the voice certifications start at the CCNP level.

0:36So if you're in either of those areas, you're in the right place. So let's get started, and dive in. So as I began to explain, this course is really for two kind of folks. So maybe you applied for a position, maybe it's a junior voice admin, or junior administrator. And within that environment, maybe you have CUCM, you have unity connection, you have phones, you also have video endpoints. You have other applications in your environment that are integrated into voice, like maybe call recording, or maybe a call center application, like Contact Center Express, but at the end of the day, you're walking into a collaboration infrastructure.

1:19Now this position maybe was internal, so you came from a different team, or this is an external position, so you're coming from outside of the company. But at the end of the day, you may lack the experience to fully understand the collaboration environment, or to administer it. Maybe your job role requires you to perform moves, adds, and changes. So when there's a new hire, or maybe an employee move to a different department. Or maybe one end point has a send channel in 1001, and they want the name change on that endpoint.

1:53Or they want the number of rings before it goes to voicemail to be different. So this may be your primary role. Again, the role of a junior admin, while the more senior folks, he or she, take care of the infrastructure. So my goal here is to lay out the foundation that you need to fully understand and administer the environment. So when you're actually doing that move out or change, that you understand what a calling search base is, that you understand what a partition is, and that we also understand some of the different options, the different knobs that you can turn within, CUCM, for example, that will make you a better administrator.

2:28In the past, I've encountered many folks who are making changes throughout the environment, but don't fully understand the impact of those changes. They just know that that person should be in this calling search base. Or this person should be assigned this number, or this partition. Quite often, when there's a new member of the team, and they renew the voice, I often volunteered my time to kind of show them the ropes. This is what CUCM does. Here's a phone booth process. I would also show them things like here's a process when we have a new hire, or when an employee leaves the company. Or when you see this type of ticket, this is what we need to address.

2:59So what I was trying to do is take the fear away of coming to a new environment, especially new technology, like voice over IP, but to also make them more comfortable. And why? Because I used to be in that spot. I remember my first day walking into the LAN WAN team, local area and wide area network, and they also administered voice not knowing anything about voice whatsoever. I was fortunate enough that they gave me an opportunity to be part of the team, understanding that I needed a bunch of training. So I had many mentors show me the ropes, take the time to show me this is how this works.

3:32And when you see this type of ticket, or this type of error, this is what this means. And that really helped with my learning curve, my confidence, and really helped me launch my career. And I truly cannot thank those team members enough for what they did for me. So that's the same approach I'm going to try to use here is, to welcome you to the team. And for you and I to go over different concepts different technologies. And we'll definitely go through a lot of demos where I actually show you a lot of these concepts. So again, my goal here is to take the fear out of the technology to make you more comfortable, and make you a better administrator.

4:04Now maybe you're here because you want to pursue CISCO certifications. Now you may remember, or may not, that there used to be a CCNA voice. That was retired. And then we had and a collaboration. And that included voice and video, then that was retired. And now we only have the CCNA. So if we navigate to the current CCNA, as of today, here we see the exam topics. But I can tell you that voice is not part of this exam.

4:36Well, there's a lot of good information here. We have some great content here at CBT Nuggets that goes over this exam, but there's not really much voice here. So if we go out to Cisco's training and certifications, and I'll scroll down to view career paths. Let me zoom in here. So here we have that CCNA exam. So that's your associate level exam. Now if you want to take them further, you can pursue the professional level exams.

5:09So here we have different tracks here, the enterprise, service provider, data center security, and we have collaboration. And here at CBT Nuggets, I have created a content for CLCOR, also for CLACCM, but if you knew the voice, there's this gap here. The expectation before you pursue your CCNP collaboration is that you have some experience and some knowledge of the collaboration environment. And that's where I find a lot of people have trouble, because they find it a little bit overwhelming to jump into these books and courses, because it requires that you have some experience in the field.

5:44And that's the reason that CBT Nuggets is allowing me to create a course just like this, to fill in that gap. And then of course, if you pass the professional level exam, and if you're a boss, you can definitely go over the CCIE, the expert level exams. So let me go back here. And I will scroll down. And here we see entry exams. So that chart that we previously looked at, so the associate, professional, and expert. And here we see entry exams. And we have here, the CCT collaboration, standing for Cisco Certified Technician.

6:18So let's go ahead and click this one. So here's the exam here. And we also have content here at CBT Nuggets for this course. But if we look at the exam topics, we see here this is really for a technician type of job role where you're deploying endpoints, or replacing endpoints. So to scroll down a bit. So here we have a little bit about the collaboration environment. So notice there's a lot of describe here and introduce, so we don't see configure here, for example. Here we see the different types of hardware we would see in our environment.

6:51So luckily, I had so many of this hardware in my lab environment. So I was able to demo that in that series. And then we have a big section here on service knowledge. So here, we're really focusing on the endpoint. How to backup and config on the endpoint. How to connect to it via SSH, how to upgrade the software on the endpoint itself, how to factory reset a phone for example. That will tell you this is what your job role is within your corporation or your company, then excellent. But we don't see here how to configure hand pallets, for example, how to administer CUCM, pointing search bases, partitions, rail patterns.

7:30That's not covered by the topics of this exam. So, again, my goal here is to fill up that gap for those junior admins, or those voice administrators that are starting out in their careers. So what if you are interested in getting CISCO certified? I initially was going to talk about this in this Nugget, but I'll save that, so I gave it enough time for the following Nugget. So with collaboration, one of the things I tried to demystify is that we just don't make phones ring. But the reality is, is that there's so many different technologies involved with collaboration.

8:02So we have our calling, but we also have conferencing. We also have video, we have call center. And call center's definitely a big one. We have call recording. We have paging. So there's a lot of technologies involved in the whole collaboration field. And that's why I love collaboration, because it's so involved, and there are so many moving pieces to it. So some final tests before we close out this Nugget, I invite you to take notes whenever possible. And unless you're one of these folks with a photographic type of memory, many of us have to take notes that we have to reference later.

8:39You can go old school, take a notebook, you can use a program like OneNote, but I think you get the idea. Whenever possible, lab up concepts. And this is something I've always had to do. Not only do I have to read about it, I also had to see it work in action. And maybe you have a lab at work, so you have a lab environment. Or maybe you're fortunate enough to build a lab at home. Now building a lab at home does take some investment, it does take some configuration, but I will tell you that journey becomes very valuable because I can lab up any concept at home, and I usually to do so before doing it in a production network.

9:17With a lab environment, you don't have any fear. So you can easily hit Apply, and OK just to see what happens. Sometimes you break your lap intentionally or not intentionally, and that's a good learning opportunity there as you try to fix it. It's best for you to have these problems in your lab than have it in your production environment, when the company is down. And you're on a bridge call as everyone is trying to figure out what happened. So at the end of this course, I'll show you how I built the lab environment I am using throughout the course.

9:50And that can be helpful in the event that you want to build a lab of your own. And then finally, dig deeper. So as I mentioned before, there are two types of administrators, or engineers, or wherever your title that you may have, one that's making changes to the environment, and then two, one that is not only making changes, but also understand what those changes are. And how it affects the environment. When it comes to troubleshooting, this person, he or she, will be a rock star, especially when it comes to troubleshooting, because they can look at a configuration and see, oh, the reason we're having this issue because this option here was set, compared to someone else who is following a template making changes and then something goes wrong.

10:38But at that point, they have to get someone involved, because their troubleshooting skills are not that deep. And I will tell you this was me at the beginning of my career just making changes because someone told me to do it a certain way. And then later, especially when I had my own lab environment, I started to dig a little bit deeper, then this became me. I was making changes to my environment, but fully understanding the implications of making those changes. So when something went wrong, I knew what area I had to investigate to see if I can resolve the issue.

11:13All right, so with that, I hope it's been informative for you. And I would like to thank you for viewing.

0:00[MUSIC PLAYING] Certifications and exams. For some of us, exams, when we hear that word, we cringe because these exams can be quite difficult. But once you pass these exams and get certified, then you're proud of yourself because of the journey it took to get to that point. So I want to take some time here to talk about these exams, how one gets CCNP collaboration certified. We'll also talk about how one gets recertified, and we'll also talk about the specialist certifications.

0:34So let's get started and dive in. So when it comes to Cisco exams, they are very beneficial, and they look very good on your resume because it tells someone that you dedicated time and resources to pass these exams. That can be very difficult, but the knowledge that you attain throughout the process by either reading a book or watching these courses at CBT Nuggets or relabbing these concepts yourself, that really goes a long way. And most employers would definitely recognize that.

1:04So let me give you an example here. So let's say you went after the Associate Exam, and you passed the CCNA. At that point, that certification is valid for three years. You may ask yourself, well, how do I recertify that certification? And that would be a good question. And if we go to the recertification policy-- and by the way, throughout this course, if you see me browse to a URL, I will have that reference within a document that you can download yourself. So you can also have that for your notes or visit that page later.

1:37So if I scroll down a bit and go under How to Recertify, and let me go here. So as we just talked about, the Associate Exam is good for three years. So we can recertify by taking another Associate Exam. So that would be the CCNA once again. Or you can take the Cisco Certified DevNet Associate or the Cisco Certified CyberOps Associate. Either one of those will also renew your CCNA. So let's say you have your CCNA.

2:08You obtain that October of 2022. Then you pass this exam maybe February of 2024. So once you pass that CCDA in February, now both certifications are good until February 2027. So I think that's definitely neat that your previous certification of CCNA also is renewed for another three years. Now for the associate, you can also pass one of the concentration exams or technology core exams.

2:44So we see here-- let me scroll back up to the CCNP exams. So if you have your CCNA and you pass either a technology core exam or a concentration exam, that also renews your CCNA for another three years. You also can attend certain Cisco-approved classes, for example, and earn CE or Continuing Education credits. And this can go toward your recertification. So let's say you go for your CCNP Collaboration, which requires you to pass the core exam and any one of these concentration exams.

3:23That will allow you to be CCNP collaboration certified. So this is also good for three years. And how would we go about recertifying CCNP? Before answering that, just know if you pass any of these tests, each one of these will give you a specialist certification. So here we go under Cisco Certified Specialist Certifications. Let me scroll down a bit. I'll choose Collaboration, and these are the same as the names that we see listed right there. So maybe you are at the beginning of your journey for your CCNP and you pass your 300-815 collaboration core control and mobility implementation.

4:04So at this point, you may not have your CCNP, but you have your specialist certification, giving you some credit for passing that exam. And what's nice about this is that you can focus on certain technologies deployed in your environment. So as we stated, this will definitely give you your specialist certifications. But once you pass one of these along with the core exam, you now become a CCNP Collaboration certified individual. So now back to our question, how do we recertify our CCNP?

4:36Let's scroll down a bit. So jumping back to Specialist real quick, if you pass one of those exams, also good for three years. And to renew that, you need to pass another, either the same or another concentration exam to renew that certification, which also renews your associate certification. Now, if you're a CCNP and you want to renew this certification, then at this point, we need to pass either one core exam or two separate concentration exams.

5:07So going back to our list here, so you're already CCNP certified. So we need to either pass a core exam in order to renew that CCNP, or we can choose to take two concentration exams. And in doing so, that will also renew your CCNP. But the beauty in all this is I have this certification here along with the enterprise. If I renew my CCNP collaboration, it automatically renews my CCNP Enterprise certification along with my CCNA.

5:38So previously, back in the day, when you got your CCNP Voice, you had to pass five exams to achieve that certification. And like every other physical exam, this wasn't easy. So let's say you pass CVOICE, CIPT1, CIPT2, and you pass CAPPS, you've passed four out of five, but you will not be recognized until you actually pass the fifth exam. And you didn't have to take in that order, but until you pass all five exams, at that point, you're recognized as a CCNP Voice. And this is the beauty about today's specialist certifications is that along your journey, you can get recognized for passing a concentration exam.

6:14So even though you may not be CCNP collaboration quite yet, you are a Cisco Certified Specialist. This also allows you to focus on certain areas. So for example, one person could be a CCNP collaboration, pass the core exam along with the automation concentration exam. Someone else might have passed the core exam, but they also pass Collaboration Cloud and Edge Implementation. So here we have two individuals, each one having a different skill set based on the exam that they passed, focusing on certain technologies.

6:45So in this Nugget, we had a discussion about Cisco exams, so how one can get certified by Cisco. We also talked about recertification because remember, the certifications are good for three years. So in order to be recognized as a certified individual, we saw the way that you could recertify. And then finally, we saw how there were specialist certifications that gave you a certain status, even though you weren't a CCNP yet. So I stated before, the certification journey is definitely worth it. It is a long and hard journey at times, but at the end of the day, you being certified can take you a long way.

7:17So with that, I hope this has been informative for you, and I would like to thank you for viewing.

0:10So in this Nugget, we'll discuss the impact of voice over IP today. The way that we communicate today is definitely different than we did 20 years ago. We'll also talk about what it means to have a convergent network. And we'll see why a business will want to use voice over IP today. So the way that we communicate is definitely different. Like today we're definitely in different times. I remember being a kid-- that's me being a kid-- and my mom and dad having to go to payphones. I was raised in the '80s, by the way. Or I remember someone leaving a voicemail on your answering machine, and you had a couple of days to get back to that person.

0:42And one can go to a park and just enjoy the view without being bothered. But now, especially with mobile phones, this is quite different. You could be at a park gazing at the water, enjoying the view. And someone can give you a phone call. It looks like a shark in the water. Point being here that anyone is really a phone call or a text away. In talking I can be stuck in my car, stuck in traffic, and partaking on a conference call. Which I'm sure many of us had done before either sitting in your car, staying at a coffee shop, or maybe you're on lunch.

1:12And now with video being really popular today, instead of having an audio conference call, you easily could be having a face to face video conference with someone. Think about instant messaging. Maybe you have a client like Cisco Webex, for example, or maybe I am in presence. In the past if I had a document here-- here's my document-- that I was working on, I could email that document to someone. And they can modify it or email it back. Maybe I can save the document on a network drive.

1:44And then the other person could access that same document, and get back to me. But now with a messaging client-- let's say this was James-- I can message James, and either attach this document right here. Or maybe it's in a shared team space, for example. Then James can immediately open up that document, make any changes to that document on the fly. Or we can have a conversation going back and forth through messages that does not involve audio though a phone call, or video. Now think about this, how many times have you been part of a group conversation about a project, or maybe an application is down, and there's a full blown conversation but just messages being sent back and forth.

2:20Someone can put in a URL there, someone can reference a document, for example. But all this being done via applications that are part of our collaboration environment. Now recently with the pandemic, we had kids at home, but still able to participate in school. So your child can have their book, and still be part of a classroom environment or virtual, with the help of video conferencing. This definitely could not have been possible 10 or 15 years ago. Think about when you call a bank.

2:51I can easily call a main number, and navigate through option 1, 2, 3, and 4. Maybe 1 is to open up an account, 2 is to report fraud, 3 is for customer service, and then 4, maybe we're talking about a business account. But here we can navigate to the IVR and eventually reach an agent, and he or she could help you with any one of those things. Previously-- and my mom and dad still do this to this day-- they drive to the bank, which is a couple of miles down the road, and wait in line to physically talk to a person.

3:24Now that's only a few examples here, but I think you get the idea. But I'm pretty sure all of us can think of many ways that voice over IP has impacted the way that we communicate. Not only in our personal lives, but also in our business and work environments. So you might have heard the term 'converge networks.' And for us to understand what that really means, let's look at a network that is not converged. So you may have a different network for your data, different network for voice, different network for video. So with data, here we can have our computers or our laptops or our printers, our scanners.

3:57I mean, tons of different devices that we can have on our data network. For voice we can have non IP phones. And those phones require special hardware or special protocols or special software to manage the environment. The same applies to our video. Maybe we have special cables, along with certain kind of hardware in order to manage that video environment. But here we see three different networks that someone or a group of people have to maintain. So here we see three different dedicated networks. This is harder to maintain.

4:27So take the example of Voice here. So maybe we have an old phone system. And let's say we have a problem with that phone, or Jane retires and now there's someone else who is sitting there. Someone has to come out who is familiar with that phone system and assist us with making those changes, or assist us with troubleshooting why that phone is not working. Same thing for video here. Maybe the network guys or those guys and girls who maintain our network are not familiar with this third party video system. So, therefore, every time we have a change or have an issue, we have to call this third party company to come out.

5:00And, obviously, this does have a cost associated with it because no one really comes out to fix your stuff for free. You may have different cabling for all three networks. You may have different protocols that are being used for all these networks. So now when we're talking about a converged network, we're talking about a network that can transmit data, voice, and video all on that same network. So here we don't have a need to maintain their front infrastructures or their front networks. All these networks can be administered by the IT department.

5:33Many times we can use the same network cabling. So in the back of a Cisco phone, we have a port that we can connect our desktop to. So our PC is connected to our phone, and then the phone is connected to a jack on the wall, for example. But here we have not only our computer, but our phone being used on the same network, being able to use network cables instead of proprietary cables used by a traditional phone system. You could use the same vendor for all three types of solutions.

6:03So if you want to you can use Cisco for data, for voice, and for video. And then these services are easier to deploy because now we can design our networks especially when we have new buildings that come up. And those networks have the ability to offer all three services. This is the reason that most cable companies will offer not only cable TV services, but also internet, along with phone services. So they bundle all these services together because it's going over the same network.

6:34And also today in some areas we have more bandwidth, definitely making this possible, especially when you're watching hybrids losing content, like Netflix and 4K, for example. Why would a business want to go with voice over IP? So we have Moves, Adds, and Changes. So previously you might have had an older telephone system, and someone had to come out. And that person, he or she would charge to perform any Moves, Adds, or Changes, or to troubleshoot an issue. So let's say we have Kelly. And Kelly is moving offices instead of calling someone out to make that change.

7:07We now have the ability to perform that change ourselves if it's inside the CUCM, for example. Kelly can just pick up her phone, and take it to their new office. Or maybe she issue a new phone, and someone on the VoIP team reconfigure their phone remotely. And then Kelly is good to go. If we spoke about, it simplifies cabling. It is not everything, data, voice, and video are going over that beta network. These services cannot be administered by IT staff. We have folks now who are familiar with your collaboration environment and applications.

7:40And they can either do these MACs, or they can make changes to the environment to better serve the business. You have application consolidation. So let's say you are a hotel. You can improve the customer experience. So maybe you have endpoints in that environment that can give guests who are staying at that hotel information about local attractions, restaurants, room services, weather forecasts. Maybe they can check out via the phone. You're providing the ability for that customer to get all the information using technology that you have provided.

8:14And this helps your staff because he or she is not bombarded with phone calls from people staying at your hotel saying, what's for breakfast today? Is there anything you do around here? I'm from out of town, do you know what the weather forecast is? Or maybe take a hospital, for example. So with a wireless phone, that being a wireless Cisco phone, every nurse could have a phone on them. So now they can make internal calls all day long using the voice over IP system. Maybe they can receive a messages on their phone. Example, they may be paged by a doctor or from the patient in room 201.

8:47Or maybe they can receive updates from hospital systems that would make them more efficient at their job. We have toll bypass. So let's say I had office in Tampa, also had a office in Chicago, and also had an office in Las Vegas. If all these sites were connected together, then someone from Tampa could call someone in Chicago as if it was a local call. I wouldn't have to pay long distance charges, for example. Why? Because that phone call is now being made internally through my network. We have features like extension mobility.

9:18So you may have a bunch of cubicles, 1, 2, 3, so that's 4. And each cubicle has a phone. So I can walk in here, and I can pick any cubicle that I want. Maybe that one right there. And with attention mobility, I can log into the phone, and, therefore, I get my extension. My name shows up on the phone, along with any other features I am accustomed to. So I can use my laptop there. I can get comfortable knowing that I have my phone there. Or maybe this is a call center environment.

9:49So if I'm an agent, and this is my cubicle there. And then we have a problem with my phone here. So what occurs here is that I am not able to work because I need someone from IT to come out and look at my phone, possibly diagnose it, and troubleshoot it, replace it. So I can easily lose one hour-- and that's being really generous-- but one hour of time where I'm not taking phone calls for this call center. Now this affects the rest of my call center because now there's many calls in queue. Customers are having to wait longer than usual because I'm unable to take phone calls. But with extension mobility, I can simply go to a different cubicle, log in, and then continue to work.

10:25Now I can still contact IT about that phone that's not working there. But for the time being, can continue to take phone calls that are coming into the call center. We have website integration. Often you go to a website, then a pop up comes up saying, hey, do you need help? And you can open up a chat session with someone, an agent on the other end. And they can assist you with your customer support issue, with troubleshooting. So that customer didn't have to dial a phone number, they simply went to your website and opted for that chat that was presented to them.

10:57So with the employee voice over IP, do we just rip and replace the old phone system? And the answer is no because that's a drastic of a change. Now we're doing a Greenfield deployment, so we are creating a network from scratch for a new company or a new office, and that may be different. So let's say you have 50 offices or locations in your environment, you may want to upgrade them to a voice over IP location by location. So we're talking more of a phased approach. That would be easier for the adoption of this voice over IP system. Plus it gives your IT staff a really great chance of a successful deployment.

11:31In fact, this is exactly what we did in one of my previous jobs. So we would go to one of those sites, maybe site A. And we would sit down with the folks and say, how many phones do you have? Keep in mind this is a site that had the traditional phone system, and we were converting them to voice over IP. Do you have voicemail? Do you have a IVR, so a menu that a customer could choose from? Do we have any phone numbers that we have to put over or port over to that new system? Are there any shared lines? Do we need switches that provide PoE?

12:03And we'll talk about power over ethernet in a future Nugget. But the takeaway here is that we will do a site survey to see what the needs were for that location. And we took that approach on a site per site basis, ensuring that we had a successful deployment as we went from that traditional PBX over to voice over IP. So in this Nugget, we went over the impact of voice over IP as we see it today. It truly changes the way that we communicate. We also talked about converged networks, and why we would want to use voice over IP today.

12:35So I hope this has been informative for you, I'd like to thank you for viewing.

0:00[AUDIO LOGO] I find many things truly fascinating-- the fact that we can just turn lights on and off in a flick of a switch. The fact that I can compose an email, hit send, and someone on the other side of the globe can receive it immediately. The simple act of making a phone call is no different. Years ago, when it was common to have a house phone, how many folks picked up the receiver and made a phone call and never thought twice about the process?

0:30So in this Nugget, I want to discuss analog signaling when it comes to the traditional phone system. We'll also talk about some of the limitations and noise on line. And this is a good conversation to have, especially if you're new to voice. I, like many folks, were new to voice at some point in time in their career. And then we'll follow up in the following Nugget where we compare this to digital signaling. So let's get started and dive in. I often wonder what people thought when the telephone first came out. I wonder if people saw the potential of the telephone, or they were like, telephone, who needs them?

1:00One of my first jobs was working at Best Buy. And I remember when there was a big announcement that they had launched BestBuy.com. And many of us sat around and discussed, why would anyone go to a website and buy something? Why not just go to a store, walk in, then look around, and make your purchase? And we were like, this would never last. So silly. And now today, most of our purchases occur online. In fact, many businesses exist today because they serve their customers online.

1:32They don't even have a building that you can walk into. So often wonder, when they created the telephone if people at that time really realized how that invention would change the way that we communicate today. So for many of us, when we were younger, maybe you had a telephone inside your house. So this phone was connected to a port, an RJ11 port. And beyond that port, there was cabling, copper wires, that connected you to the CO, or the Central Office. In the US, it's referred to as a CO, or Central Office. You might have heard this also referred to as a public exchange.

2:06But a CO is a building that contains all types of switching equipment that the telephone company maintains. So you would purchase a telephone line from the phone company. They would assign you a phone number. And anyone in the world can call you by dialing that specific phone number. And a copper wire connected you to the PSTN. Now, the PSTN is short for Public Switched Telephone Network. And it's really this gigantic network that transmits voice data. And this PSTN has been around since the 1800s. And this network is a circuit-switched network.

2:40And we'll see here shortly why they call it circuit switched. So let's say you had additional homes. They also would have their own phone lines, each phone line being connected to the CO. This makes sense because if you have a connection to the CO, then the CO could facilitate those phone calls. So this makes better sense than having a connection between all these homes. And we have a connection here, here, here, here. And I think we get the idea. So we all connect to the central office instead.

3:11And they manage the infrastructure. So when Pedro goes off hook, he hears a dial tone. He may dial the phone number for this pet store. So that phone call goes from his home, through those copper wires, over to the CO, and they route that call appropriately till eventually it gets to that pet store. And then that phone is ringing. So someone answers that phone call. And now we have a dedicated circuit between Pedro and that pet store. And this is why the PSTN network is called a circuit-switched network, because you have a circuit between the source and destination during the entire duration of that phone call.

3:50So when Pedro is talking here, how do we have his voice carried over to the front end to whoever he's talking to at the pet store? His voice is converted to electrical signals. And those signals carry the property of that voice, maybe the volume that Pedro is talking at, his pitch. The properties of that copper wire, the electrical signals, the voltage and frequency and current, that is used to transmit Pedro's voice to the other end. And those signals are converted back to sound.

4:21And that's how the other person on this end is able to hear Pedro's voice. And these same electrical signals are used for signaling purposes to determine if a phone is on hook. So this is where the receiver is currently on the phone. It can help us to determine if the phone is off hook. So if someone picks up this receiver, at that point, we hear a dial tone, when the phone is ringing. Or maybe we call someone, and the phone is busy. So all these messages are being sent over electrical signals.

4:52So as I mentioned before, this phone plugs into an RJ11 jack. In fact, let's go out to Amazon. Here's a good picture here. This is a network connection. So this is RJ45. And if we scroll down a bit, here we see a RJ11. So it's kind of tough to see. But if you ever see it physically in person, this jack here is smaller than a network jack in regards to size. And you can kind of tell that here based on this picture.

5:24So going back to our phone here, how does the phone know that Pedro pressed 1 or pressed 3. After all, we need to dial phone number to be able to reach that pet store. And that's done via DTMF, Dual-Tone Multi-Frequency. And DTMF is really the sounds that are created when a certain key is being pressed. And this is exactly how we interact with the phone system, for example, so it knows what number that we want to dial. Or maybe you are dialing an IVR and want to hit option 2 for sales, for example.

5:55DTMF is how the IVR knows that you have pressed option 2. So for example, if we hit option 1 here, there's actually two tones being transmitted at the same time, hence the name dual-tone, multi-frequency. So in fact, there's a neat site-- Online Tone Generator. And here it allows you to hit the different keys. So if I hit 1, [TONE PULSING] you can hear 1 there. Now I'll hit 9, and you should hear a difference. [HIGHER TONE PULSING] Then we go 1. [ALTERNATING TONES PULSING] How about 0?

6:27[TONE PULSING] So you can see if I dial 190, their tones are different. [TONES PULSING] And again, the reason being, when I hit 6, for example, we have two different frequencies being transmitted at the same time. So one of the problems with analog signaling is the distance limitation. Those signals, which are strong at first, begin to fade over time. And that's why throughout the infrastructure we have repeaters. And what they do is regenerate that signal as it gets from a source to a destination.

7:00So this increases the distance that analog signal could possibly travel. But these repeaters cannot differentiate between the voice traveling over that telephone wire and also any noise. So for example, if you had static on that line, as that analog signal gets sent to point A to point B, that noise will also be regenerated by those repeaters. So possibly, when that signal gets to a destination, the sound may be distorted, or it just become difficult to understand because of that noise that also was regenerated.

7:35And shortly here, we'll talk about different types of noise that might exist on an analog signal. So another limitation could be wiring requirements. So imagine if you are a business and you needed many phone lines to come into your business. So let's say this building had 15 people. So you may see a scenario where you have 10 to 12 phone lines to accommodate your business. So that's 10 to 12 different set of copper wires. And you might have seen this before.

8:05Here's an example of a business with copper wires being terminated on these blocks. And this can become quite messy. But here's another picture there. And what needs to happen is that someone needs to have a butt set, take these clips here, and that's how we would connect to that phone line. Maybe we're trying to identify what phone number that line is. So this here could be your phone lines coming in from the PSTN. And then this could be the copper lines throughout your building.

8:37So let's say if Kelly is moving from the first floor to the fifth floor-- let's say it's right here, for example-- then we have to move that line to the connection in her new office. That could be right there. But many times these connections are not labeled correctly. So you have to find which one is 813-555-7777. And that's where you would use your butt set here. And once you identify it, at that point, you have to start moving or punching down copper wires to a different location.

9:10So when it comes to line noise, what are some examples of line noise? We'll go to another site here. And I will have a document that you can download that references all these URLs that I'm browsing to. But this one is recognizing and categorizing symptoms of voice quality problems. Now, I like this site because they actually have some samples of what you could hear out in the field. So one example you may hear is clicking. So let me turn my volume up. Let me see if we can hear this.

9:40"Green is the color of her kind, quickness of the eye deceives the mind. Envy." Now, I have no idea what that guy is talking about, but there's clipping that you can hear or pauses in that conversation. So it's almost cutting off what that gentleman is saying. Let's see what else we got. Scroll down a bit. Here's crackling. [CRACKLING INTERFERENCE] [INAUDIBLE] So many of us have heard that before.

10:13Let's do one more example. And how about hissing? [INAUDIBLE] So I hope you can hear that hissing in the background. And there are only a few of the noises that you may hear on an analog line. And then many times, if you check out your infrastructure and that seems to be OK, so you check your wiring. Everything looks good on your end. You have to get with your telephone company. And then they come out and check their infrastructure-- so their cabling to your building, for example, to see if there's an issue with that wiring.

10:51Or there could be a problem with the CO to wherever that circuit is terminated at. So what could cause that line noise? Faulty wiring. So maybe the copper wire is not shielded properly. Or maybe it's not punched down all the way on that punch block. It could be the weather. So for example, we used have one building where when it rained, the ground around that building got really saturated. That's my water. And then we would get complaints saying, hey, I have static on the line, or I have whatever issue when I'm making a phone call.

11:23And what happens here is that the moisture gets on those copper lines and causes some of that line noise. We have corrosion. Some of these wires are exposed to the elements. So over time, those copper wires corrode and induces some of this noise or maybe electrical interference. So humming is caused when your copper wire may be too close to power lines. This is one example where electrical interference may cause line noise. So in the following Nugget, we'll talk about digital signaling and how that differs from the analog.

11:54And in closing, there are some parts of the world that are doing away with the PSTN. They're telling businesses they have to migrate to voice over IP, or they will no longer have any phone services. And the reason being because a lot of this infrastructure for the telephone company is older and expensive to maintain. So in this Nugget, we went over analog signaling. We saw how it worked. Here we are using electrical signaling to transmit the sound of your voice from you, the source, over to the destination. And this is done over the PSTN.

12:26We also spoke about DTMF, some of the limitations of analog signaling. And we also talked about possible line noise that you may encounter on an analog line. So I hope it's been informative for you. And I'd like to thank you for viewing.

0:00[AUDIO LOGO] In our previous Nugget, we had a discussion about analog signaling. That's when our voice or the sound of our voice was carried over electrical signals. Now, when it comes to digital signaling, we'll see that the difference comes down to 1's and 0's. So in this Nugget, we'll discuss digital signaling and why it was beneficial for the PSTN to switch from analog to digital. So around the 1960s, the telephone company was transitioning from analog to digital.

0:35When making a phone call, we still had the analog voice, but it was being digitized upstream. And this allowed telephone companies to increase the capacity within their networks. So here we're transmitting more phone calls simultaneously over that same copper wire. So the sound of your voice is being converted to 1's and 0's. And this is done via PCM, or Pulse Code Modulation.

1:05So here we are sampling the data, and we're converting each sample to some type of numeric code. So let's say this was the sound of your voice. We're sampling that data many times over a time period. So the time frame here could be 1 second, each sample having some type of numerical value. So in analog, we had a limitation of distance. And this really wasn't a problem with digital signaling, the reason being because we're transmitting 1's and 0's across the wire.

1:40And we're doing so along those same lines that we're using to make our phone calls. So there was a gentleman whose name was Harry Nyquist. And he found that he could reconstruct audio streams by taking samples that numbered twice the highest audio frequency that was being used in the audio. If that sounds confusing, raise your hand please. So let's break that down. So the average human ear can hear frequencies from 20 to 20,000 hertz.

2:13And as you get older in life, that number decreases. Human speech can be heard from 200 hertz all the way to 9,000 hertz. Now, studies find that understandable human speech-- and I'll abbreviate it by HS-- is from 300 to 3,400 hertz. So when we say understandable, we have enough sound quality there to identify the remote caller and their mood. So Nyquist was looking at the frequency from 300 to 4,000 hertz.

2:50Going back to the statement I made earlier, Nyquist found that he could reconstruct audio streams by taking the samples that numbered twice the highest audio frequency. So here, the highest numbered frequency is 4,000. So multiply that times 2. We have 8,000 samples that are being taken every second. Remember each sample having its own numerical value. Now, there's 8 bits in each sample.

3:21So you multiply that. That gives us our 64,000 bits per second, or this gives us our 64 kilobits per second. Now, we haven't gotten to codecs yet, but G.711 is a popular codec. This codec is uncompressed, but this codec consumes 64 kilobits per second per phone call. So definitely, there is no coincidence between these two right there. So after all that, what I want you to walk away with is that digital signals use numbers to represent the voice that is coming out of your mouth, which is different than analog which is using electrical signals.

4:02So when you see the term digitizing voice, we're taking our analog, converting that to digital. Then on the other end, that digital is converted back to analog. And that person hears a sound of your voice. And with digital signaling, we're able to make more phone calls over that same copper wire. This is a very big reason why telephone companies went from analog to digital. We are less susceptible to noise compared to analog signals.

4:34And during data transmission, that digital signal can be checked for errors and then corrected as it goes from a source over to a destination. And then we don't have the distance limitation that we had with analog signaling, because we're not dealing with electrical signals. I hope this has been informative for you, and I would like to thank you for viewing.