What is VoIP

Voice over Internet Protocol (VoIP) is a term used to describe the transmission technologies for delivery of voice communications over Internet protocol (IP) networks such as the Internet.   Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband, broadband telephony, and broadband phone.

Internet telephony refers to communications services -voice, facsimile, and/or voice-messaging applications—that are transported via the Internet, rather than the public switched telephone network (PSTN).

Companies that offer VoIP services include:

Vonage: http://www.vonage.com/index.php?ic=1

Skype: http://www.skype.com/

VOIP.com: http://www.voip.com/

The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression of the signal into internet protocol packets for transmission over the Internet; the process is reversed at the receiving end.

VoIP systems control the set-up and break-down of calls and use audio codecs which encode speech allowing transmission over an IP network.

There are three common methods of connecting to VoIP service providers:

  1. An analog telephone adapter (ATA) can be connected between an IP network (such as a broadband connection) and an existing telephone jack.
  2. A dedicated VoIP phone that connects directly to the IP network and uses technologies such as Wi-Fi or Ethernet.
  1. An Internet phone or Digital phone – software that can be installed on a computer that allows VoIP calling without dedicated hardware.

Reservations about adopting VoIP service.

  1. IP networks can be unreliable compared to the circuit-switched public telephone network, and does not inherently provide a mechanism to ensure that data packets are delivered in sequential order, or provide quality of service guarantees.
  2. Voice and data packets travel over the same network and the system is more prone to congestion and denial of service attacks.
  3. IP phones and VoIP telephone adapters which connect to routers or cable modems typically depend on the availability of electricity which make them susceptible to power outages.
  4. Emergency calls cannot easily be routed to a nearby call center because the nature of IP makes it difficult to locate network users geographically.
  5. Since it is a computer-based technology, Voice over Internet Protocol telephone systems are as susceptible to attacks as PCs.
  6. Routing VoIP traffic through firewalls and network address translators can be a problem.
  7. Some VoIP solutions do not support encryption, so, it is relatively easy to eavesdrop on VoIP calls and even change their content.
  8. Some VoIP providers may allow a caller to fake the caller ID information, potentially making calls appear as though they are from a number that does not belong to the caller.
  9. The ability to send faxes over VoIP may be limited.

10. Another challenge for VoIP implementations is the proper handling of outgoing calls from other telephony devices such as DVR’s, satellite television receivers, alarm systems, and other similar devices.


  1. ^ “Voice over Internet Protocol. Definition and Overview”. International Engineering Consortium. 2007. http://www.iec.org/online/tutorials/int_tele/index.asp..
  1. http://en.wikipedia.org/wiki/VoIP
  2. http://www.fcc.gov/voip/

~ by 1ofthe1s on June 12, 2009.

5 Responses to “What is VoIP”

  1. I have had VoIP for my home telephone service for the last 2+ years. First we used BroadVoice for the service, and only recently switched to AT&T. Set up was simple. We did however discover an echo on the line later found to be related to our MTA box (beta code from a test trial through work.) The echo was easily identified and eliminated. With both BroadVoice and AT&T, the quality of service (dial tone, sound, speed, connection) has been great.

    Unfortunately, one disadvantage with BroadVoice was that they could not offer us a local area code, apparently because “there were not enough numbers available.” This was a bit inconvenient since friends, schools, businesses then had to call us long distance. Interestingly, we learned to rely upon our cell phones more and more, to the point we almost gave up a permanent home line.

    You bring up some excellent pros and cons of VoIP service; in particular, I am acutely aware that in a power outage and therefore a phone outage, cell service is critical for me. I live in California; should a big earthquake occur causing a power outage, cell phone carriers would likely be jammed with the flood of in/outbound calls to loved ones.

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  3. This is the second blog post I’ve read on VoIP and I must say it seems that the problems or drawbacks to this type of phone service outweigh the benefits. It may be very useful for some business or work for some individuals, but I would have to have a lot more convincing before I would switch to VoIP.

  4. Well, I have to allow myself to comment on the reservations concerning VOIP. I really don’t like the fact that the service is not as reliable as the traditional phone services. I guess companies see the benefit of using VOIP because there is no need for a lot of equipment. Well, I would like for my phone service to work on a regular basis. If the power goes out, you have no way to contact anyone. If the companies’ servers are down for the day, you can’t use the internet either! How inconvenient is that! I wouldn’t like if someone was calling me from a fake number either! It seems like the more advance the phones become, the more issues are attached to them. I don’t see how anyone can muster the fact of not being able to use 911 as needed! That is so unreliable! Well, I’ll most likely use the service for a short period of time just to see how it affects me but overall, VOIP is just a new way to communicate!

  5. My only real experience with VOIP is the few times I have utilized Skype’s calling feature. This has actually come in quite handy & economically valuable for me, because I have used it to talk with a wonderful net-friend of mine who lives in Germany. Rather than spend money using our cell phones, we’ve been able to talk internationally long distance for free, which still amazes me that such a service is available! I really only have positive feedback to offer; the phone/voice clarity has been great and as of yet, I’ve not experienced any noticeable transmissions either. I’m fairly certain I wouldn’t like VOIP as my primary or only mode of phone service, but as a free feature from a website that has also allowed me to IM with my friends as well, I’ve thoroughly enjoyed utilizing the calling feature to talk with people more often than I would otherwise be able to.

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