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What is VoIP?

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Voice over Internet Protocol.

It is a telephone that uses Internet resources rather than traditional telephone lines.

Mr Craig Brownell
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voice over IP

Voice over Internet Protocol, also called VoIP, IP Telephony, Internet telephony, Broadband telephony, Broadband Phone and Voice over Broadband is the routing of voice conversations over the Internet or through any other IP-based network.

Protocols which are used to carry voice signals over the IP network are commonly referred to as Voice over IP or VoIP protocols. They may be viewed as commercial realizations of the experimental Network Voice Protocol (1973) invented for the ARPANET.

Voice over IP traffic can be deployed on any IP network, including those lacking a connection to the rest of the Internet, for instance on a local area network.



In general, phone service via VoIP is free or costs less than equivalent service from traditional sources but similar to alternative Public Switched Telephone Network (PSTN) service providers. Some cost savings are due to utilizing a single network to carry voice and data, especially where users have existing underutilized network capacity they can use for VoIP at no additional cost. VoIP to VoIP phone calls on any provider are typically free, whilst VoIP to PSTN calls generally costs the VoIP user.

There are two types of PSTN to VoIP services: DID (Direct Inward Dialing) and access numbers. DID will connect the caller directly to the VoIP user while access numbers requires the caller to input the extension number of the VoIP user. Access numbers are usually charged as a local call to the caller and free to the VoIP user while DID usually has a monthly fee. There are also DID that are free to the VoIP user but is chargeable to the caller.


VoIP can facilitate tasks that may be more dificult to achieve using traditional phone networks:

* Incoming phone calls can be automatically routed to your VoIP phone, regardless of where you are connected to the network. Take your VoIP phone with you on a trip, and wherever you connect to the Internet, you can receive incoming calls.
* Free phone numbers for use with VoIP are available in the USA, UK and other countries from organizations such as VoIP User.
* Call center agents using VoIP phones can work from anywhere with a sufficiently fast Internet connection.
* Many VoIP packages include PSTN features that most telcos normally charge extra for, or may be unavailable from your local telco, such as 3-way calling, call forwarding, automatic redial, and caller ID.


VoIP allows users to travel anywhere in the world and still make and receive phone calls:

* Subscribers of phone-line replacement services can make and receive local phone calls regardless of their location. For example, if a user has a New York City phone number and is traveling in Europe and someone calls the phone number, it will ring in Europe. Conversely, if a call is made from Europe to New York City, it will be treated as a local call. Of course, there must be a connection to the Internet e.g. WiFi to make all of this possible.
* Users of Instant Messenger based VoIP services can also travel anywhere in the world and make and receive phone calls.
* VoIP phones can integrate with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books and passing information about whether others (e.g. friends or colleagues) are available online to interested parties.


VoIP technology still has a few shortcomings that have led some to believe that it is not ready for widespread deployment. However, many industry analysts predicted that 2005 was the "Year of Inflection," where more IP PBX ports shipped than conventional digital PBX ports. This date has been moved on an annual basis and only now (mid 2006) is it beginning to happen. However, many purchasers of VOIP ports just want a phone, so the statistics can be misleading when interpreted by marketeers.


One drawback is the difficulty in sending faxes due to software and networking restraints in most home systems. However, an effort is underway to define an alternate IP-based solution for delivering Fax-over-IP, namely the T.38 protocol. Another possible solution to overcome the drawback is to treat the fax system as message switching system which does not need real time data transmission. The end system can buffer completely the incoming fax data before displaying or printing the fax image.

Internet Connection

Another drawback of VOIP service is its reliance upon another separate service - an internet connection. The quality and overall reliability of the phone connection is entirely reliant upon the quality, reliability, and speed of the internet connection which it is using. Shortcomings with internet connections and Internet Service Providers (ISPs) can cause a lot of grief with VOIP calls. Higher overall network latencies can lead to significantly reduced call quality and cause certain problems such as echoing.

A few business VOIP Providers (like Unity Business Networks) overcome this challenge using dedicated connections (point to point T1s) between a client location and the VOIP Providers gateway facility where VOIP is converted back to traditional local phone service. Using a point to point connection with specialized routers which prioritize packets, the highest quality of service can be achieved.

Many VOIP users still maintain a traditional analog voice line (business line) which allows them to utilize a traditional fax machine when needed and can also be used to call 911 service if you have an analog phone on the fax machine as well.

Power Outages

Another drawback of VOIP is the inability to make phone calls during a power outage, but this problem also exists with many phones used with conventional land lines and can be remedied with a battery backup. During a power outage you also have the choice to forward your phone to your cell phone or another phone number so you would still be able to receive calls. Although you can't call out on your home phone system during a power outage, at least you can still receive calls.

If VoIP is used in solitary LAN (with no Internet connection), it would consume more resources compared to a PABX.

Mr Rupert Symss
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Have you seen the Vonage ads that flood the TV nowadays? That is VOIP. The acronym itself stands for Voice Over Internet Protocol. This, in simple terms, means that your voice calls are converted into digital output, sent over the Internet, and converted at the other end to voice output again so that another person at the other end can be called through their normal phone.

Due to the nature of the technology, you get cool features. For instance, sitting in Philadelphia, you can get a Los Angeles area code, thereby any one in LA can make local calls to you! (Your calls to anywhere in US is free so you do not pay extra either).

Plus, if you travel to, say, France, you can take your number and phone with you and plug into a broadband Internet connection, and your home phone will ring wherever you are!

Cool, huh?

Mr Krishna Prasad Canada
(Expert Rating 1954)
   Member has an expert rating of 1000+
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