Sometimes, to discuss VoIP, we must discuss what VoIP is not — in this case, VoIP is not POTS.

POTS is the common nickname and acronym for Plain Old Telephone Service – you know, the “traditional” phone jack in your wall. The POTS system uses technology that is basically unchanged since the early 1900’s. The wires may be upgraded, sure there’s more features, but the telephone technology in use via POTS is essentially the same technology introduced before there were airplanes, highways, or even household refrigerators.

Background, aka Trivial Knowledge that Patrick would call Interesting

The telephone was invented by Alexander Graham Bell, who along with Thomas Edison, created a method of transferring voice over long distance through the use of connecting wires. Basically, one telephone would be physically connected to another.

Operators manually connected the two-parties together allowing the transfer of voice to occur. Human operators have since been replaced with automatic exchangers; where a computer determines the party you are wishing to talk to and making the connection. This device for automatic transfer is sometimes referred to as a telephone switch and the POTS engineers like to call their telephone network a Public Switched Telephone Network, or PSTN.

VoIP vs POTS

At VoIP Tech Chat, we are huge (no fat jokes please) proponents of Voice over Internet. Go Know. Of course, if we didn’t believe so strongly in Internet Telephone, then having a VoIP Tech Chat website would be a pretty stupid idea.

VoIP differs from POTS in many ways. Fundamentally, the end result is the same. In both systems you pick up a phone, dial a number, and talk to the other party. Other than that, the systems are extremely different. VoIP is digital and does not use wires to physically connect devices. VoIP works by digitzing your voice, sending it over the Internet to the destination, and then having it return to audio on the other side. (If you haven’t done so, you should really read “What is a VoIP?” by Patrick and Fred. It’s a great read and even mentions George Michael)

Like anything, both VoIP and POTS have their own Pros and Cons. Despite POTS technology remaining virtually unchanged since the early 1900’s, the reliability of POTS is unmatched. In fact the level of reliability achieved by POTS is the quintessential “five nines” reliability standard. This means, that with POTS, you can expect to have an outage for less than 6 minutes a year. (That’s why at&t and Verizon engineers make big change)

Now, let’s contrast five nines reliability to VoIP reliability. First, remember that VoIP requires a synergy of several service providers to get a dial tone. (Editor note: first quintessential and now synergy? Wow. Today must be vocab day at Voip Tech Chat) The two main players in VoIP are your Internet Service Provider and your VoIP Service Provider.

Let’s say for example that you were using Vonage as your VoIP provider and Comcast as your ISP. Comcast home Internet service has a 99.9% uptime average; which is very high for the industry. In fact, it would be hard pressed to find an ISP that provides you better than 99.9% uptime. Of course, even though 99.9% uptime is amazing, this translates to 44 minutes of downtime per month. Vonage doesn’t list their uptime average (in their defense, most VoIP companies do not list their uptime. We couldn’t find any for Vonage, VoIP.com, or Packet 8.). So, let’s assume Vonage has a 99% uptime (which is being generous according to the posts we read from users). This translates to an additional 7 hours of outage per month.

For reliability, there is no better choice than POTS. (Which is why many people keep a landline active for 911 service) But if you’re an average phone user willing to weigh Cost against Reliability, VoIP starts to look amazing. Of course, we’ll cover VoIP advantages in another article.

Remember, that in a nutshell, VoIP is telephone over Internet (for more details, check out our What is a VoIP? post). Now, a huge part of Internet Telephone is the quality of your Internet service. If we were to ask you, “Mr./Ms. Voip Tech Chat Reader, how good is your Internet connection,” what would you say?

If you were to answer very good, great, excellent, phenomenal, or sweet mother of all that is good and holy, my Internet connection rocks — well, you’re going to have no problem with VoIP. In fact, you’ll probably recommend VoIP to all of your friends.

Now, if your answer is ok, decent, or alright, then it’s time to consider upgrading your service or consider holding off on VoIP.

Yes, in the back, you have a question?

Patrick and Fred, your podcasts are hysterical. My question is about QoS. How can I test my quality of service and what do the test results mean?

Wow. Excellent question. And thanks for the complement. We really appreciate it.

There are many free websites that you can use to test your quality of service; especially for VoIP use. Our favorite is TestYourVoip.com by Brix Networks. At TestYourVoip.com, you choose a city from the Call Destinations box (choose one that’s the closest to you) and then the site mimics a VoIP call. At the end of the test (about 30 seconds), you’re given a score and an option to “See Detailed Results.” We recommend clicking the detailed results button (don’t worry… you won’t wake up in the Matrix).

The important test results to look at are (and again, don’t worry, we’ll explain them):

• Latency
• Packet Loss
• Jitter

Latency

Latency is a term used in many professions, such as IT and medicine. In common terms, latency means delay. In our context, latency is the delay from when the digital signal leaves you and is reached by the other end (like the person you’re talking to). 

If your test shows a latency of more than 300 msec, you’re going to experience some weird talk-over effects during the call. The biggest factors for improving latency will be your networking equipment (like your router, firewall, modem) or your Internet Service Provider.

Jitter

You ever play scrabble? With scrabble, there are all these nice letters and you mix them all around and what comes up is a really mixed up shuffled version of what you started with. That’s jitter. Jitter for VoIP would be when part of your voice reaches the other side out of order.

Bottom line? Jitter is when your voice gets scrambled like eggs at the waffle house.

Any jitter of more than 50 msec is going to cause a delay in your calls and make talking on a VoIP line pretty annoying. To improve your jitter results, you’ll want to check your networking equipment or talk to your Internet Service Provider.

Packet Loss

When you speak into a VoIP telephone, your voice is turned into digital signals and sent to the other party. These signals are called packets, and packet loss is when some of those signals don’t get to other side. Think of packet loss as the airline losing your luggage.

If your packet loss is greater than 1%, you will experience some skipping or clipping while you’re talking. A 1% packet loss will result in a skip or clip of your conversation approximately once every 3 minutes.

To improve your packet loss, you’ll either want to talk to your Internet Service Provider, upgrade your connection, and/or make sure you’re not downloading or uploading large data while on the phone.

Thanks for taking the time to read this, and if you have any questions, click the old comments link and ask away!

Also, be sure to check out these posts:

• What is a VoIP?
• What is DTMF?
• How does 911 work with VoIP?