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PSTN & Cellular Networks

Anonymous — Sat, 14 Aug 2010 07:06:55 CDT

Media gateways enable multimedia communications across networks using multiple transport protocols such as ATM and IP. They are essentially a translation unit between various telecommunications networks such as PSTN, NGN, 2G, 2.5G and 3G radio access networks or PBX. The focus of this article, however, will be the public switched telephone network (PSTN) and how it relates to PBX VoIP technologies.

How are PSTN and VoIP tied together?

Although PSTN is mostly a digital gateway, it was originally a network of fixed-line analog telephone systems. Some critics say that even its digital capabilities are starting to age in light of the VoIP revolution, and these same critics further speculate that the eventual role of PSTN will only be to serve the Internet and little else. The need for conventional phones will be eliminated over times as VoIP technology comes to predominate. For that to happen, every household will need to acquire a broadband connection of some type to replace the classic phone system. Although broadband penetration is growing, it is still not an available service in some areas, which means for the time being that the old reliable telephone is safe from extinction.

Primary uses for PSTN as a media gateway

In addition to dial-up or broadband users at home, PSTN is often used by businesses as well. Large companies often link to the PSTN through limited gateways, like a large private branch exchange system (PBX). VoIP PBX, known also as IPBX, is gaining in popularity because it works on an Intranet setup within the business. A PBX setup is more secure for most purposes and situations in which there might be an issue leveraging other forms of VoIP over an open line. In addition to heightened security, PBX offers the same features (e.g. voice mail with e-mail or other advanced features) you find with conventional Internet VoIP systems.

What’s offered with PSTN and PBX media gateways?

As with other types of VoIP, PBX on a PSTN offers the following standard features:

Automated directory services
Automatic ring back
Call transfer
Call forwarding
Call waiting
Call conferencing
Custom greetings
Department message boxes
Hold music
Speed dialing
Voicemail

The future of VoIP and media gateway

PSTN will still be required for purposes other than just as a source for VoIP systems in the near future. Although the technology is growing rapidly, there remain other issues that make it impossible at this point to totally replace PSTN. As one example, not all VoIP programs and systems support important functions like 911 access. It must be said, however, that there very well may come a day when PSTN is strictly used as a media gateway, and nothing more.

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Benefits of GSM Gateways

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Benefits of GSM Gateways

Anonymous — Mon, 26 Jul 2010 01:21:32 CDT

Fixed-to-mobile calls (i.e. a call placed from a landline phone to a mobile phone) are typically more expensive. The call needs to pass through different telephony networks, and can thus cost more than an in-network mobile-to-mobile call. When a call is placed from a fixed line to a mobile phone, it needs to pass through a PSTN to a mobile interconnect facility called the Mobile Telephone Switching Office (MTSO). This routing costs your phone company money, and they pass those costs along to you in the form of increased call rates. As more and more people choose to use their mobile number as their main point of contact, calling expenses can rise quickly.

According to gateway manufacturer QuesCom, calls from landlines to GSM phones represent between 30 and 60 per cent of your total telephone bill. This call volume has generated the need for a GSM gateway. A GSM gateway eliminates costly routing from a fixed line to a mobile phone. When you dial a number with a GSM prefix, the GSM gateway automatically routes your call directly to the cellular network instead of through your fixed-line provider.

Some gateways have multiple SIM cards and can automatically choose the SIM card with the best rate. Charges are lower when the SIM card is part of the same network as the destination number. Think of it as a type of least cost routing (LCR).

According to GSM gateways and VoIP GSM gateways manufacturer Hypermedia Systems Ltd, cost reductions and call cost savings can start straight away, without changing any organizational dialing habits and without impacting on any arrangements with call service providers/vendors or fixed line carrier. Moreover, companies can better utilize special low mobile phone packages (VPN rates) available in the market.

VoIP GSM gateways take the concept a step farther by allowing you to call directly from an IP to a GSM network. Again, with its installed SIM cards, the gateway can place relatively cheaper GSM-GSM calls instead of IP-GSM calls. These gateways can support H.323 and/or SIP to communicate with your IP PBX or IP phone.

The VoIP GSM gateway allows businesses to significantly reduce phone expenses. According to gateway manufacturer 2N, companies can lower their fixed-to-mobile call costs by at least 50% without incurring any negative impact on voice quality. 2N also predicts a return on investment (ROI) at six months or less after deploying the gateway, and offer an online savings calculator to help you estimate just how much you could save by deploying a VoIP GSM gateway (http://www.2n.cz/case_studies/savings_calculator.html).

VoIP GSM gateway manufacturers are quick to point out additional benefits of their products beyond cost savings. Most include integrated SMS capabilities, enabling office users to send SMS messages from their PCs. And gateways that include multiple SIM cards can easily reroute calls to another SIM when there’s a failure on a GSM network. This serves as a network backup for critical communications.

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VoIP Service

Anonymous — Mon, 07 Dec 2009 14:24:35 CST

911 Enable is a single provider for all your E-9-1-1 needs, 911 Enable delivers E9-1-1 call routing and location management solutions for today's IP networks. 911 Enable’s solutions recognize the challenges to 9-1-1 posed by VoIP and converging technologies. Using a flexible approach, 911 Enable offers equipment agnostic solutions which can be integrated with both legacy and IP-based technologies.

5PCom is an emerging VoIP Service Provider based in San Diego's "technology district" Sorrento Valley, CA, USA. The company offers quality Residential and Business VoIP service plans, at lower prices than better known competitors. Use your own adaptor or have one provided with refundable deposit. You can port your number for free (subject to availability), and receive "added value pricing" with commitment (optional). Additionally, 5PCom requires no start-up fee, and your first month of voip service

Freevoice is a voip provider specialized for Predictive and auto dialer traffic. $.019 per minute 6/6 billing with no short duration call penalties

VoiceTelOne is a VoIP provider based in Coeur d'Alene, Idaho. VoiceTelone allows you to make and receive phone calls through your high-speed Internet connection using an ordinary telephone and adapter. Service plans include Limited and Unlimited Residential and SMB calling throughout the U.S. and Canada. Business plans include various Hosted (virtual) PBX configurations.

MyNetFone is Australia's leading VoIP service provider for home and business. If you have friends and familyin Australia let them know they can now call you at low rates and PSTN-quality. The company also offers complete business solutions including milti-line VoIP and Virtual PBX, so if your company has a branch in Australia they can saveon expensive equipment and enjoy free calls.

OpenTone Communications Philippines Inc. is one of the leading VOIP provider in the Philippines today. A VOIP company offering affordable VOIP international plans for both businesses and residential, allowing subscribers to make unlimited long distance call to the US, Canada, Europe, Middle East, Philippines, and other Asian countries. OpenTone communications voip products and services are Call Centers business solutions, Internet Cafe, Hosted PBX, Virtual DID, Global VOIP Call, Middle East bundle, Asia bundle, Europe bundle, Unlimited US/Canada.

Tutorials

Anonymous — Thu, 08 Oct 2009 16:47:55 CDT

Click to Call with PHP-SIP

Business VoIP Comparison

Anonymous — Fri, 02 Oct 2009 17:30:32 CDT

Business VoIP Comparison website helps you make the right decision on your VoIP provider. Browse providers by price, feature or popularity. Read user reviews and comments.

Google Talk

Anonymous — Thu, 14 Feb 2008 05:02:07 CST

Google Talk

Service overview

Google Talk is much like Skype, but brought to you by the popular search engine company. It likewise can be used for free PC-to-PC calling and instant-messaging, but it does lack some of the features boasted by Skype. On the other hand, Google Talk offers features Skype doesn’t provide.

Google Talk vs. Skype

First, let’s compare these two popular programs side by side:

Google Talk, like Skype, requires a PC Internet connection, a microphone and a speaker, or a headset, in order to send and receive calls.
With Google Talk, you can talk to people who are also using Earthlink, Gizmo Project, Tiscali, Netease, Chikka, and MediaRing, which they call a "federation." With Skype, in order to communicate PC-to-PC, the people you are contacting need to be using Skype as well.
Both VoIP providers are free services and have instant-messaging capabilities.
Calls can be made anywhere in the world by either service.
Google Talk has no voicemail capabilities, so you can only talk when the other party is online, whereas Skype provides voicemail.
Google Talk has no conference or video capabilities, while Skype does.
The setup process is similar for each -- the program must be downloaded, installed, and then registered before use.
Google Talk functions with Windows 2000, Windows XP (Home & Pro), or Windows Server 2003, while Skype works on Windows 2000 or XP, Mac OS X, Linux or Windows Mobile 5.0, and Windows Mobile 2003.

Customer reviews

CNET.com users rated Google Talk higher than Skype, giving it a 9.3 out of 10, even though Skype has more features. The bulk of reviewers cited the lack of "bloated" features as the reason why Google Talk is so attractive. The service is simply a program for users who aren’t looking for too many bells and whistles. In other words, Google Talk is a VoIP program that allows them to talk to friends and instant-message from time to time. People also like the idea that the service is compatible with other programs.

As far as sound clarity rates, many Google Talk users seem reasonably satisfied, though the quality is perhaps not better than that of competitive VoIP services. Other positives of the free software include reports that it lacks advertisements and apparently doesn’t make drastic reconfigurations to the PC operating system or browser.

The bottom line

Although the instruction pages at Google Talk are more technical in nature and tone than those of other VoIP programs, users will find installation to be easy if they've ever done any software installing before (and who hasn't?). If you want emoticons, PC-to-phone dialing, or other "add-on" features, you're advised to look elsewhere. But if you’re a person who simply wants to chat with someone via your computer, then Google Talk seems to get the job done quickly, effectively, and with no major changes to your computer registery that could cause conflict issues.

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Fax

Anonymous — Tue, 29 Jan 2008 08:39:25 CST

Traditional faxing represents a significant chunk of a company’s communication expenses. An estimated 40% of calls between the United States and Europe at any given time are fax calls; that figure moves toward 50% between the United States and Asia. Faxing over standard phone lines thus results in a large quantity of expensive international calls.

Faxing over the Internet can eliminate those hefty long-distance charges. When you send a fax over IP, the fax data is transmitted as packets through the public Internet or company Intranet instead of the PSTN (Public Switched Telephone Network). If the fax transmission ever has to go through the PSTN (i.e. if the destination fax is a traditional fax machine), it’s only for the local portion of the call. Companies can send faxes throughout their own private IP network for free.

There are two methods for faxing over the internet: Fax over IP (FoIP) and Fax over VoIP. FoIP represents the only way to reliably send a fax through the IP network, although there are plenty of tech-savvy individuals who can successfully fax over VoIP. Both methods are covered below.

Fax over VoIP

You might expect to be able to send faxes over your VoIP line, just as you can over a traditional phone line. However, it’s not that simple. VoIP lines are not really designed for modem use. For starters, they typically utilize low bitrate codecs to maximize the number of voice calls. These low bitrate codecs cannot transmit modem signals properly (i.e. an 8 kbps G.729 codec cannot convey a 9.6 kbps fax modem signal correctly). Secondly, there’s the issue of packet loss. Losing packets isn’t that significant in voice calls, since you can still understand what the other person is saying. However, data dropout is a different matter. A few lost packets can lead to an error message or dropped call when faxing.

Of course, faxing over VoIP can be done, and both Vonage and AT&T CallVantage offer fax services with VoIP. Here are a few recommended steps:

You should set up the call using a 64 kbps codec. If you’re using Vonage, the dedicated fax line will use this rate. And with AT&T CallVantage, the second line uses this rate by default as well.
If you can’t get access to a 64 kbps channel, set the BAUD rate on your fax machine to 9600 bps or lower.
Set your resolution to standard
Turn off ECM

Information Source

http://www.voipfrustration.com has information on how to change the settings on over 600 fax machines, and also includes a link to the fax manuals.

Fax over IP

Another faxing option is FoIP (or Fax over IP); this function is similar to Voice over IP, but is optimized for fax transmission. In this model, a fax is sent over the Internet to a fax server nearest the destination fax. Then the fax is transferred to a phone line and sent like a normal fax. Because the fax has traveled over the Internet for most of its transmission path, total transmission costs are much less than those associated with conventional faxing. The ITU has developed two standards for FoIP: T.37 and T.38. T.37 refers to a “store and forward” faxing, where the fax is delivered as an e-mail attachment and then delivered to the destination fax over the PSTN phone line. While this method lowers transmission costs, it cannot provide real-time verification that your fax has been properly received. If you’re used to walking up to a fax machine, sending the fax, and getting your confirmation printout, T.37 is not for you.

ITU’s T.38 standard provides real-time fax delivery over IP and works like traditional faxing. T.38 fax gateways are equipped to handle any delay, jitter, or packet loss in the packet network to minimize their effect on the fax transmission. The standard also reduces the bandwidth needed to send image data.

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joip

Anonymous — Mon, 07 Jan 2008 14:22:17 CST

Joip
Joip Forum

Service Providers

Anonymous — Wed, 02 Jan 2008 16:15:01 CST

This section provides service overview information for Skype, Google Talk, Vonage, and VoiceTelOne.

Skype

Service overview

Skype is a free communications program from the inventors of the peer-to-peer filesharing program KaZaA. Skype allows you to talk to anyone in the world using your Internet connection, speakers, and a microphone (or combo headset).

Installing Skype is quite easy, and all you need to do is follow five simple steps to make calls:

Download the program from skype.com
Register for the service
Install the program on your computer
Plug in your headset, speakers, or USB phone
Start calling your friends

Making outside calls

If you’d like to make calls to landline or cell phone numbers all around the world, Skype also has a paid program called Skypeout. At present there are no setup or subscription fees, but Skype does charge for calls depending on your location and where you are calling. Essentiallly, you set up a credit system and when you make a call, the funds are deducted from your account.

Who’s "online"?

With 254 million people already downloading Skype worldwide, it’s quite possible you or someone you know is already using Skype’s VoIP service. On average, about 5 million people are using Skype every minute.

Features worth mentioning

Skype emphasizes the importance of sound quality. As they explain on their site, with normal telephones you can only hear sounds from 300 Hz to 3 kHz. With Skype’s VoIP service, sounds come in much clearer, so any communication sounds more natural and crisp. The Skype service provides voicemail, so you don’t miss anyone’s phone messages. Skype can also function as an instant-messaging program like AIM, MSN, or Yahoo Messenger.

Customer reviews

CNET.com rates Skype an 8.0 out of 10. Many user comments match this rating as well.

Comments proclaim the Skype VoIP service to be cheap and easy to use. Calls to other Skye users are clear and speedy. However, when using the landline feature, some people did experience problems communicating with the person they were calling from their PC. Other users also claimed to experience problems with trying to set up an account for the paid services. The same users also said Skype customer service failed to provide targeted information for getting to the bottom of specific technical issues related to account management. The problem apparently lies more with the company taking the funds, Moneybookers, than with Skype.

The bulk of the consumer reviews suggested that Skype’s free service is superb when it comes to PC-to-PC connections and to some PC-to-landline connections.

The bottom line

For people who aren’t extremely tech-savvy but still want to try a VoIP service, Skype is an excellent choice. Current customers also claim that the money they save talking PC-to-PC or even PC-to-landline is worth a few "glitches" here and there. To paraphrase one reviewer, for the price of free you can’t beat it.

Google Talk

Service overview

Google Talk is much like Skype, but brought to you by the popular search engine company. It likewise can be used for free PC-to-PC calling and instant-messaging, but it does lack some of the features boasted by Skype. On the other hand, Google Talk offers features Skype doesn’t provide.

Google Talk vs. Skype

First, let’s compare these two popular programs side by side:

Google Talk, like Skype, requires a PC Internet connection, a microphone and a speaker, or a headset, in order to send and receive calls.
With Google Talk, you can talk to people who are also using Earthlink, Gizmo Project, Tiscali, Netease, Chikka, and MediaRing, which they call a "federation." With Skype, in order to communicate PC-to-PC, the people you are contacting need to be using Skype as well.
Both VoIP providers are free services and have instant-messaging capabilities.
Calls can be made anywhere in the world by either service.
Google Talk has no voicemail capabilities, so you can only talk when the other party is online, whereas Skype provides voicemail.
The setup process is similar for each -- the program must be downloaded, installed, and then registered before use.
Google Talk functions with Windows 2000, Windows XP (Home & Pro), or Windows Server 2003, while Skype works on Windows 2000 or XP, Mac OS X, Linux or Windows Mobile 5.0, and Windows Mobile 2003.

Vonage

Service overview

Since first launching VoIP service in the United States in 2001, Vonage (www.vonage.com) has racked up more than one million subscribers and has completed over 1.6 billion VoIP calls as of January 2006. The company offers SIP-based VoIP service to both business and residential customers throughout the United States, Canada, the United Kingdom, and Mexico. Vonage provides what’s called “stand-alone” VoIP service, meaning customers must already have broadband access from another provider.

Service packages

Vonage’s biggest claim to fame is cheap phone service. They offer both residential and small business packages. The residential unlimited plan includes:

Unlimited calling anywhere in the U.S. and Canada
Voicemail (that includes both e-mail alerts and online message retrieval)
Caller ID
Three-way calling
Call forwarding
Call waiting

Residential customers can pay extra for an additional fax line or 800-number;

Vonage's small business unlimited plan offers the same basic feature set as the residential plan, but also includes a dedicated fax line. Vonage offers a lower-cost tier of plans for both residential and business customers based on limited monthly usage.

Target markets

Vonage targets the residential/SOHO (small office/home office) market. For the most part, customers are not especially tech-savvy and are attracted by the promise of low-cost phone service. After signing up for service, customers are shipped a small VoIP gateway (or ATA) within a few days. Installation is simplified as much as possible, and is essentially plug and play (provided you don’t have too complicated a setup). With the gateway, you can connect your regular telephone to the Internet.

Industry profile

Vonage has pumped large amounts of money into marketing and advertising campaigns. In 2005, they spent 220 million on Internet banner ads alone (that’s 71% more than last year’s top advertiser, according to Nielson/NetRatings). The company spends about $200 for every new subscriber. Company CEO Jeffrey Citron has a bold vision, isn’t afraid of risks, and can raise money. In May 2005, Vonage received $200 million in venture funding — representing the largest single funding in telecommunications since 2000.

Vonage's aggressive ad buys have paid off thus far. Vonage boasts the highest market share for North American residential/SOHO VoIP subscribers. According to a Infonetics report, Vonage leads the way with 39%; Time Warner holds 25% and Cablevision has 19%.

However, many industry analysts are skeptical about how much longer Vonage will continue to enjoy the lead-dog position. Their market share dropped from 36% in Q1 2005 to 32% in Q2 2005. And their Q2 share (36%) was actually their lowest share in nine months. Vonage was early to market, but now must compete with larger cable and phone companies like AT&T, Verizon, and Time Warner. Another major factor is that Vonage is a “single play” provider; they offer only VoIP service, whereas cable companies can offer bundled packages including data, voice, and video services.

But the organization isn’t relying on marketing dollars alone to retain its position. Vonage tries to stay ahead through innovative services and applications. They just launched a new portable WiFi handset directed at the consumer market. They also released a Western European virtual phone number service that allows subscribers to sign up for an inexpensive secondary number, and select from a range of European numbers. Friends, relatives, and colleagues can now call them in the United States for the charge of a local call.

VoiceTelOne

Service overview
VoiceTelOne VoIP Phone Service (www.voicetelone.com) allows you to make and receive phone calls through your high-speed Internet connection using a standard phone and adapter. VoIP provides the same or better quality as traditional phone lines, but you pay far less for all of your calls worldwide. Call any phone, anywhere, it works just the same as your traditional phone service.

For Residential Phone Service
To use VoiceTelOne's VoIP Internet phone service you'll need a broadband connection to the Internet like cable, DSL or high-speed wireless. When you order VoiceTelOne service you'll receive a small piece of equipment called an ATA (Analog Telephone Adapter) that adapts your phone for use over the Internet. Simply plug the adapter cable into your high-speed Internet connection, unplug your phone from the wall and plug it into the adapter and you're ready to start making calls.
You'll save money each month and get all the same features that traditional phone companies charge extra for, at no additional cost.

VoIP Hosted PBX for Small Businesses
VoiceTelOne's Hosted PBX system delivers a complete suite of enhanced business VoIP hosted PBX functions and features over your broadband Internet connection. No on-site equipment is necessary except phones, and all setup and configuration is done via a web portal. VoiceTelOne's proprietary network and system can handle any size business from just a few extension to large enterprises with thousands of extension and phone numbers distributed across the nation.

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voip.com

Anonymous — Mon, 10 Sep 2007 07:12:23 CDT

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Disadvantages

Anonymous — Sun, 26 Aug 2007 06:54:51 CDT

VoIP has been heralded as the next great invention for your personal or business computer. The technology allows you to connect and place phone calls to anyone in the world for free -- or at least for the price of an Internet connection. But just as every cloud has a silver lining, you also need to realize that even if something shows a bright side, it often has a dark side to match. VoIP is no exception.

There are four main disadvantages of VoIP to consider:

Slow connection – One of the key disadvantages of VoIP is you can’t just pick up the phone and make a phone call. You need to start your computer, make sure your modem is connected, and only then can you initiate a call. In an emergency situation, you might not have time to boot up in order to call 911. What's worse, for some VoIP services, numbers like 911 and 411 (information directory) aren’t even available.
Stability – When it comes to disadvantages, this one tops the list. Since a strong Internet connection is a prerequisite, if you don’t have the proper connection speed, you’ll experience a lower quality of service. Also be mindful that the connection while using the VoIP "line" must be well maintained throughout each call. If your ISP has a habit of dropping out unexpectedly, then so will your calls.
Service compatibility – Unlike phones and cell phones, VoIP programs have to be compatible (or, in many cases, the same) in order for you to communicate with someone else. For example, a Verizon Wireless cell phone user can call anyone, however in the case of VoIP service, you must use the same service provider (AKA program) or communication won’t occur. Service incompatibility is one of the disadvantages of VoIP that many providers are working to fix, but at present it remains an issue.
Security – As with any new technology, you have individuals who are trying to "crack the code." VoIP users are at a disadvantage when it comes to experiencing computer worms, viruses, toll fraud (for pay services), or port scanning. Firewalls and other security systems might help bolster security, but VoIP services could put your computer and the information it holds at risk.

Potential VoIP users need to look at both sides of the coin and make an informed decision as to whether the current set of disadvantages outweighs all the potential benefits of adopting VoIP.

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design of voip

Anonymous — Mon, 23 Jul 2007 03:08:10 CDT

There is no abstract available for this page revision.

Skype is the only decent VOIP service

Anonymous — Fri, 12 Jan 2007 12:03:59 CST

There is no abstract available for this page revision.

Basics of VoIP

Anonymous — Mon, 30 Oct 2006 16:26:52 CST

VoIP it might sound like a scary new technical term with little practical near-term relevance, but actually it’s an exciting communication protocol that more and more people are adopting every day. This section provides an overview of the basics of Internet voice adoption.

There are three primary benefits to adopting VoIP:

1) It’s inexpensive. Instead of paying for both an IP cable modem line and a landline phone, users only need a cable modem to connect to the Internet to initiate and receive phone calls.

2) Calls are free. Phone companies charge you for calls in terms of minutes, whether you're billed under your service plan or as an add-on. Some long-distance and international calls result in additional charges to your phone service bill. With VoIP, you can call anyone, anywhere in the world, at any time. The only cost to you is your Internet connection, which, chances are, is a bill you’re already footing since you’re reading this information on the web.

3) Portability. You can’t take your home phone with you on business trips or vacations, but with VoIP you can. Much like a cell phone, as long as you have a connection (in this case an Internet connection) you are able to make and receive calls from anywhere. Simply plug in your laptop to an Internet port to send and receive calls.

Now keep in mind that VoIP isn’t a "standard" capability of any computer. You need to download software in order to make it function.

There are two basic types of VoIP software:

Gateways – Software that connects to other users through a third party, also known as PSTN (Public Switched Telephone Network)
Peer to Peer – Software that doesn’t use a central, or third-party, service provider, but instead is a direct connection to the person you’re speaking with on VoIP.

Which program you decide to use is really up to you. What is most important is that there is a large assortment of providers out there offering either type of software program – and, best of all, the majority of these programs are offered to users at no charge.

Can VoIP replace the old reliable analog telephone? Some people believe that eventually it will. As communication systems improve and more people become wired into the World Wide Web via cable service, the need for the push-button phone will go the way of the dinosaur.

Topics in this section:

Getting Connected

Anonymous — Sun, 29 Oct 2006 05:21:50 CST

Technology advances proliferate every single day -- though they make our lives better, each new product or service necessitates a certain amount of adaptation and adjustment, if not technical ability.

This section was compiled to help the VoIP-uninitiated understand the hardware components (adapters, phones) and service plans required to best leverage the technology for making calls, faxing, and conducting wireless communication.

In this section:

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A Community Guide to VoIP Phone Service

wetpaint — Mon, 02 Oct 2006 10:56:35 CDT

What is VoIP?

If you’ve had Internet access for the past year you’ve probably noticed more and more people talking about something called VoIP, or Voice over Internet Protocol. Despite the technical-sounding term, VoIP is actually a quite simple -- yet revolutionary -- communication technology. VoIP facilitates a process of converting the analog voice signal from your phone into a digital data signal that is transmitted over the Internet.

Now what does that mean in practical terms, or, in other words, why should you care? In the plainest terms, VoIP transforms a standard Internet connection into a means to place free – yes, free! – telephone calls anywhere in the world, circumnavigating the phone company and its pesky nickel-and-diming altogether.

While the number of people in the United States who have cable Internet connections isn't yet an overwhelming majority, the more the technology advances, the less need there will be for maintaining a secondary traditional phone service in the home. Ma Bell might not be scrambling just yet, but thanks to VoIP, eventually all you’ll need to reach out and touch someone is your cable modem, speakers, VoIP software, and a microphone.

wikiVoIP.org was created to present and explore some of the basic principles, connectivity requirements, and network characteristics of this emerging technology.

How to use this site

Take the quick tour or start contributing your knowledge about VoIP right away by clicking the EasyEdit button at the top of this, or any, page. If you notice something missing, start a new page. The more you contribute your questions, answers, or perspectives, the more the community benefits. If you don't see the information you need or want, request a new page here.

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pilmo

Anonymous — Wed, 31 May 2006 10:05:54 CDT

There is no abstract available for this page revision.

About Us

wetpaint — Mon, 27 Mar 2006 14:46:54 CST

What is wikiVoIP?

wikiVoIP was created to provide a collaboratively built storehouse of information to help people understand in plain terms the components of this emerging communications technology and its potential uses and benefits in their lives.

You don't need to be a recognized expert to contribute -- the invitation to participate is extended to anyone who is intrigued by the technology. This site is guided by the notion that the best information on any subject comes from those with authority born out of experience and interest. Every addition you make enriches the unique and authoritative voice of the content and community.

We welcome you as a new contributor and ask you to help determine where the conversation goes from here.

What is Wetpaint?

wikiVoIP is powered by Wetpaint. Wetpaint provides free hosting and tools for the creation of websites like this one, featuring the community-building elements of wikis, blogs, and forums. It’s an exciting new tool for communication and content creation that’s focused on ease of use, enabling anyone, regardless of his or her technical abilities, to easily collaborate and connect with others who share a common passion.

How do I get started?

The best way to get an overview for how to use and contribute to this site is to view the demo. For answers to more technical questions, check out the wikiVoIP help section. We've also written a code of conduct to help frame guidelines for appropriate and respectful community participation.

For a more human touch, reach out to one of the site moderators or another community member if you have a question or require help. You can find the moderators in the “Meet the Moderators” section in the bottom right-hand corner of most pages.

Low-Bandwidth Solutions

Patty — Fri, 24 Mar 2006 17:59:17 CST

VoIP requires a large amount of bandwidth…or does it? There may be alternatives to consider if you wish to adopt VoIP but also happen to be a dial-up or low-bandwidth user. Some individuals report that Vonage's service works reasonably well for dial-up VoIP, but the company doesn’t officially state their services are available to low-bandwidth users.

More is better but…

Some people simply don’t have the luxury of a high-bandwidth connection but that doesn’t mean they have to be left behind when it comes to VoIP. One company, PCPhoneline.com, claims to work with dial-up VoIP connections as low as 19.2 kbps. The site sells IP phone products, as well as offers downloads in the protocols of Skype, SIP, or IAX2. It should be noted, however, that some users claim to have experienced firewall problems when PCPhoneline.com tried to gather information from their computers. As the users themselves explain, this situation probably happens because the software is checking to be sure that multiple copies are not installed. Still, for those who might be leery about an outside company gaining access to their computers, it could be an issue. Other paid providers of low-bandwidth, dial-up VoIP include Cuphone.com and Azatel.com. In particular, Azatel designs, manufactures, and integrates SIP & MGCP products such as Analogue Terminal Adapters (ATA).

Paid low-bandwidth VoIP options include:

PCPhoneline.com
Cuphone.com
Azatel.com

Perhaps using a paid VoIP service is out of the question. If that’s the case, then there is an alternative to consider. It’s free of charge and loaded with features and options, unlike many VoIP programs on the market today.

The new wave of free low-bandwidth, dial-up VoIP

Wavigo.com offers a free program that works using peer-to-peer (P2P) technology, in combination with SIP. Dial-up speed must be at least 33kbps, which many computers and ISPs can keep up with in today’s Internet market. An added bonus is it only takes 10mb of RAM to run, as compared to other VoIP programs that require 25mb or more.

Beyond simple VoIP

Greg Parker, creator of SpiderSoftware, offers more than just VoIP with Wavigo. The program is in fact an "all-in-one" P2P extravaganza. With Wavigo, users can talk, do SMS-text, instant-message (to Yahoo, MSN, AIM, ICQ, Google, Skype), transfer files, e-mail, and send offline messages. You can also access a wealth of information (news, sports, and weather information) or conduct web searches using Wavigo. Wavigo is also a full multimedia player, so you can manage podcasts or play games if you like. Future features will include WavOut, which will allow users to make outgoing calls to landline and cell phones, and a mobile version of Wavigo for your PDA.

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Codecs

Patty — Fri, 24 Mar 2006 17:58:30 CST

The codec plays one of the most important roles in Voice over IP. It determines voice quality and how much bandwidth is needed for a call. The rule of thumb is the higher the voice quality, the more bandwidth is required for the call. Several different codec standards exist that allow network designers to choose the best compromise between sound quality and bandwidth requirement.

Here’s how it works. Your voice, an analog signal, is sampled several thousand times per second and converted into a digital signal. If the codec calls for compression, the signal is then compressed to significantly reduce the bandwidth needed for transmission. The compressed signal is put into packets (each packet typically contains about 20-30 ms of audio) and sent over the IP network to its destination, where it undergoes a reverse process to be converted back to an analog speech signal.

VoIP codecs are designed specifically for the frequency range of the human voice. If you tried to pass a music sample through one of these codecs, the sound quality would not be very good.

VoIP codecs are defined and standardized by the ITU, International Telecommunications Union. Each uses a different algorithm to sample, compress, and packetize voice signals. The table below shows the main codec types with their respective bitrate and voice quality. Voice quality is represented by a MOS (Mean Opinion Score). MOS is a popular subjective measurement of voice quality, also defined by the ITU. The voice sample is judged by a group of individuals and then given a score on a scale from 1 (bad) to 5 (excellent).

Compression delay (also known as packetization delay) is the amount of time the codec needs to do its job. Cisco suggests that as a general rule you should aim for a packetization delay of no more than 30 ms.

Some degree of compression is usually required for networks. Take DSL service, where upstream links are usually limited to 128 kbps. If a VoIP provider uses G.711 (uncompressed codec), the actual bandwidth needed for a single channel is about 100 kbps, meaning VoIP providers could only offer a single voice channel over the link. By compressing voice, the provider can now offer multiple channels over the same link.

Codecs can contain other advanced tricks to optimize voice quality and bandwidth use. Some codecs use PLC, or Packet Loss Concealment, to compensate for lost packets. With PLC, codecs try to minimize the impact of packet loss by filling in the gaps with audio that’s acceptable to the human ear. There are other methods for dealing with packet loss, but PLC is the most common.

Some codecs also support silence suppression. Essentially, this follows the rule of “don’t send any data if no one is talking.” This method is far more efficient than the traditional phone system (or PSTN) which keeps a full channel (in both directions) dedicated to a call regardless if anyone is talking or not.

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