The other day, the phone rang and it was my friend Flo calling from overseas. We hadn't talked in quite a while, so we nattered on for an hour or so. It wasn't until she said "Well, this call has cost me $1.20" that I realised she was Skyping me – calling me from her computer using Internet telephone software. On her end, no phone was involved at all, merely a headset microphone, Skype software, her computer and her broadband Internet connection. From my end, it seemed like a normal phone call. Maybe with a touch more echo on the line than usual, but otherwise indistinguishable from a call from my brother across town.

This is VoIP in action. It's a technology which has been lurking around for some time, appearing in nascent form in a number of applications over the years. Now, it's really starting to make a splash.

What is VoIP?

VoIP, also known as Internet telephony, is a phone system which runs on the Internet instead of the traditional public switched telephone network, or PSTN.
The rather strange acronym – you'll sound like a cross between a Chihuahua and a frog when you say it – stands for Voice over Internet Protocol. The 'voice' part of that is easy enough to understand; the 'Internet Protocol' part refers to a method used for packaging and addressing data on a network.

The Internet itself is an example of a packet-switching network. On the Internet, information is passed around in packets known as datagrams. When you send any form of data across the Internet – whether it is text, images, video clips, audio – the data is first chopped up into chunks. Each chunk of data not only contains part of the original data, but also a packet number indicating where it fits in the stream of data packets created from the original, plus the destination address. Your computer sends the packets to a nearby router; the router checks the address and passes each packet on to another router, and so on until the packet reaches the appropriate address. Packets are routed along the least congested paths, so not all packets will follow the same route to their destination. Once all the packets arrive at the destination, they are reassembled, using the packet numbers, into a complete whole once more.

Contrast this with the public telephone system, which is a circuit-switching network. In a circuit-switching network, when you want to transmit information between two points, you establish a connection between those points and maintain that two-way connection for the duration of the call. So, when you pick up the phone, you first listen for a dial tone indicating a connection to your local telephone company, you dial the number, your call is passed through the local switch and possibly through a number of intervening switches to its destination where the phone rings, the person you called answers, and a circuit is created, remaining open until one of you hangs up.

Clearly, in a circuit-switching network you don't need any of the addressing and ordering details required for transmitting data on a packet-switched network, and the direct link between the two parties involved makes it a very reliable form of communication.

The downside to circuit switching is that it's not very efficient. It requires a dedicated, if temporary, channel between those communicating, and its wasteful of that resource: much of a phone call consists of silence on the part of at least one of the parties involved, and there are frequent if brief times when no-one is talking. While packet switching may not have the simplicity and reliability of circuit switching, it is far more efficient because it eliminates all the 'silences' on the network and transmits only when data – whether it be a packet containing a little chunk of a conversation or some other form of data – is present. And there's no need for a dedicated circuit; due to the addressing scheme built into the data packets, your packets can be intermingled in a stream of packets from many other users, with each finding its way to the correct destination.

PC-to-PC VoIP

VoIP comes in a variety of flavours, from simple software applications to complete phone-replacement solutions.

At the low end of the spectrum are PC-to-PC voice applications. These apps let you chat with fellow computer users who are running the same software. Most instant messaging programs, including AOL Instant Messenger and Windows Messenger, provide a voice feature like this. In addition, there are numerous VoIP applications which do the same thing, including the aforementioned Skype and Firefly.

To use these applications, you and the people you wish to call need the same instant messaging or VoIP program installed, a microphone and speakers and, of course, an Internet connection. The calls are free – apart from what you pay for your Internet line.

While voice connections are doable on a dial-up connection, keep in mind that audio data is bulky and consumes a lot of bandwidth, so the faster your connection, the better the audio quality and the less likelihood that bits of the conversation will drop out. You'll get the best results if both you and the person you're conversing with have high-speed connections.

You can also improve the quality of the calls by using a headset-microphone. If you're intending to do any amount of VoIPing, a quality headset/microphone combo is a worthwhile investment, preferably with a USB connection to your computer.

Softphones

The next level of sophistication is programs which let you make calls not only from PC-to-PC but also from PC-to-phone. These programs are sometimes called 'softphones'. Skype and Firefly are examples, as is the venerable Net2Phone.

With a softphone, you can place PC-to-PC calls for free to anyone using the same softphone program; you can also call regular landline or mobile telephones for a per-minute charge. Usually that charge is much, much lower than the rate you get when making traditional phone-to-phone calls, often just a few cents a minute for calls to the UK and the US.

Why so cheap? Because a long-distance softphone call travels most of the way along the Internet, carried along with all the other data on the network. It only jumps off the Net and onto the traditional phone network when it hits a gateway near the phone number you dialled. From that point on, the call travels over the traditional phone network, and you get charged for that short segment of the call. Most softphone providers get you to prepay for calls using a credit card; you can then speak all you like until you've used up your available minutes, when a recharge is required.

The quality of softphone calls is dependent on the speed of your Internet connection, the type of microphone you use to make the calls, and the compression technology used by the particular softphone. If you have a high-speed Internet connection and a good headset microphone, call quality should be quite acceptable for most uses, although you may notice a little more line noise and echo than with traditional phone calls. You can also improve the quality by buying a USB phone, such as the one offered by Freshtel for its Firefly service. Such phones also integrate neatly with the softphone itself giving you an automatic dialling directory.

Most softphones provide better voice quality than the voice feature of traditional instant messaging programs because of the more sophisticated compression algorithms they use. Because voice occupies a lot of room when transmitted, the software first compresses it before sending and then decompresses the voice data stream at the receiving end. The result is not always perfect. In practice, I've found softphones are fine for calling siblings and colleagues, but just not good enough for calling my hard-of-hearing, octogenarian mother.

Several softphones provide additional features, such as multi-party phone calls and voicemail, which make them even more attractive.

tip: bandwidth usage
If you pay per megabyte for your Internet connection, it's handy to know how much your voice calls will consume. Both Firefly and Skype use around 3 kilobytes/second in a one-to-one call. That's around 10 megabytes per hour.

Broadband phones

Phone-to-phone VoIP takes your computer out of the equation and lets you use your regular telephone to place calls across the Internet. To do this, you need:

Broadband phones provide the best quality of all VoIP alternatives. In the US, where VoIP has a head-start on most of the rest of the world, companies such as Vonage have encouraged hundreds of thousands of customers to abandon their phone lines altogether. Broadband phone services also often provide a smorgasbord of features, many of them included with the monthly service charge. Engin, for example, offers 3-way calling, voicemail, V-mail (email notification of voice messages), address screening, scheduled redirection and much more.

There are pitfalls to dumping your traditional phone service, though. Your broadband phone is dependent on your Internet connection; if the Net goes down, so, too, does your phone. If you've not been particularly satisfied with the quality of your high-speed Internet service, you'd do well to avoid relying on it for your phone service.

Other things to consider: you may have to go through hoops to have multiple handsets around your house; you may have to abandon your old phone number; you won't have a White Pages listing; and your Internet phone may become a potential target for virus writers and voice-mail spammers.

Videophone

Well over 10 years ago, a company delivered a pair of videophones to the offices of PC User magazine where I worked at the time, so we could check out this "up and coming" technology. There's no doubt the videophones were cool; they were also very expensive, at around $AUD2000 a pop, and the quality of the video left a lot to be desired. Our assessment was that videophones were nowhere near ready for prime time.

Jump forward over a decade and videophones are still very much stuck in the "up and coming" basket. That's because while audio consumes a lot of bandwidth, video consumes far, far more and it requires new hardware on both ends of the connection. It also looks like mobile phones may have stolen this sector of the market for themselves, leaving traditional landline phones and PC-based phones out in the cold.

Still, there have been videoconferencing applications available for many years, programs which let you make PC-to-PC video calls. CU-SeeMe was one of the best-known of these video apps. It was sold some time ago to a somewhat iffy outfit which appears primarily interested in developing the "adult" section of the market. But the author of CUSeeMe, Tim Dorcey, now has another videoconferencing application that does an even better job. iVisit gives you PC-to-PC voice and video calls, multi-person video conferencing, file sharing and Web co-browsing.

To use iVisit, you need a Webcam, an Internet connection (as fast as possible), microphone and speakers, and an iVisit account. A Lite account is free, and it gives you one-to-one, 60-minute video calls at 160 by 120 resolution; PC-to-PC audio calls; instant messaging and chat; limited file sharing; and the ability to do remote presentations. For $US39.95 per year, you can upgrade to iVisit Plus and get high quality video and audio conferencing; high-priority bandwidth and high-resolution video; and unlimited file sharing. There are also options for businesses and educational institutions, including iVisit Server for managing multiple virtual conference rooms.

For larger businesses, companies such as Webex offer advanced voice conferencing for around $500/month and up, while Microsoft has recently ramped up its videoconferencing offerings including Live Meeting.

tip: voip and firewalls
You may have to fiddle with your firewall settings to get your softphone to work. For instance, Firefly requires port 4569 to be opened in some environments. Skype seems to work pretty well with most firewalls. If you encounter a problem, check out these detailed instructions.

Step-by-step: How to Skype

Skype is one of the most popular softphones. To get started with Skype, download and install the free software. Note that Skype uses peer-to-peer technology, grabbing idle cycles from your computer's processor to route calls by other Skype users. It doesn't appear to cause a noticeable drain, but if you primarily use Skype for outgoing calls, remove the tick (checkmark) beside Start Skype When The Computer Starts and, when you're not using the program, right-click its icon in the taskbar and choose Quit.

The first time you use Skype, you'll be prompted to choose a Skype name and password. You should also set up the program to work with your preferred microphone. Click File Menu -> Options -> Hand/Headsets and select your device from the drop-down lists.

To add a contact for PC-to-PC calls, you'll need to know their Skype name. Alternatively, you can perform a search for them using the Skype directory, but if they haven't provided details about themselves, you won't have much luck. A quick email to them asking for their Skype name may be in order.

Once you've added a contact, making a phone call is as easy as double-clicking their name on the Contacts tab. For more options, right-click the name.

If you want to make PC-to-phone calls, you'll need to set up a Skype Out account and prepay for calls using a credit card. On the Start tab, click the link to go to your account page and then follow the prompts. Once you've funded your Skype Out account, when you add a new phone contact, type in the phone number preceded by a plus sign and the country code (for Australia, that's 61, for the US 1, for the UK 44) and omit the 0 for area codes. For example: +61 (2) 9555-5555. A number in the US might look like this: +1 (504) 123-4567.

Want to talk with more than one person at once? Use a tele-conference. On the Contacts tab, click the first contact you want to call, then hold down the Ctrl key while clicking all other contacts to be invited. Then click the Invite Selected Contacts To A Conference Call button and wait while each participant answers the phone.

© 2005  Rose Vines

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