The problem: Internet Telephony has an hard life in today's Web. Most connected PCs are cowardly hidden behind firewalls, their ports blocked, and almost every company uses NAT, because IP addresses are a precious good. In short, because of this situation existing Internet Telephony systems do not "Just Work".
Instead, Skype got almost everything right: I instructed my uncle how to install and use Skype the day after teaching him how to move that curious arrow with the “mouse”; I did not have to implore my megacorp’s Network Administrator to evoke his black magic with the company’s firewalls “just to chat with mummy”; and I did not feel left behind on my Linux box, since Skype runs natively on Linux, Mac OS X, and Windows.
How Skype manages to work flawlessly in almost any situation is roughly explained here: however, despite considering myself a geek, I don’t feel the need to know that anymore: Skype has become a real tool, not one of the many “toys” we use to play with and dissect, none of which survives more than a few days of hype and excitement.
Program characteristics and usage
Skype installation is easy and fast, and you don’t need to answer and endless list of questions to be registered; as soon as you are logged in, you can start adding contacts to your list.
Here you'll notice that all the fancy user search capabilities of other Instant Messaging platforms are missing: not a big handicap, since Skype does not (yet) aim to be a socialization tool, offering limited (and currently quite disappointing) support for free chat, named "Skype me". On the contrary, focus is centered on convenient communication with existing contacts, since by default authorization is needed to add buddies to the list, and blocking annoying users is a matter of a couple of clicks. This also eliminates worries about unsolicited messages: think about bots with sexy screen names and avatars mass-ringing everyone, and dictating a link to the usual paysites -- what a dream for spammers, what a nightmare for users!
And these sexy spam-voices would be very convincing, too: quality of audio communication is excellent at 128Kbps, and a number of different sound codecs are automatically chosen by the system, so that connections should be possible also with smaller pipes. Amazingly, lag is usually almost unnoticeable, and echo-cancellation algorithms work perfectly. In short, if you are on a DSL or better line, you'll not miss the traditional telephone.
In addition, all communications between users -- voice, instant messages, files -- are always encrypted using AES. New skype releases also feature "conferences", where up to 5 people can be connected simultaneously.
PC-to-PC calls are obviously free, but calls to regular phones are also possible at interesting rates, depending solely on the destination country, by buying SkypeOut credit: this is very convenient for outgoing calls, however, unlike other VoIP products, there's no way to receive calls from regular phones.
A negative note: Skype does not use the SIP standard, so it can not interoperate with other Internet Telephony systems; this is however largely justified, since most of its advantages come from using a new protocol instead of SIP, which does not work well in firewalled enviroments.
The windows version also supports USB handsets, a very easy to use piece of hardware: it allows to answer and initiate calls just like you would do with a real telephone, offers more privacy than the speakers + mic combo, while being more convenient than traditional "call center operator" headsets.
Clients for Mac OS X and Linux
The Mac OS X and Linux clients are perfectly functional, despite being a bit late with regards to the windows version, still missing some minor features. However, their progress is fast, and the Skype website also hosts dedicated forums, where you can see frequent posts by developers, strictly interacting with the user community.
The Linux client uses the QT toolkit but does not require KDE; it will also take advantage of the freedesktop.org "notification area" standard, thus placing a very useful icon on the GNOME or KDE panel. Being closed-source software, a lot of exciting opportunities, like evolution integration, can not be implemented by the community: however, developers promise an API, probably based on D-BUS, which should allow hackers to easily intagrate Skype with existing software.
This represents a crucial challange for Linux on the desktop, as we have a well-done closed source software with smart developers using the latest of the freedesktop technologies: how well can proprietary applications be integrated in the free desktop enviroments? This is one of the first experiments, let's wait and see the outcome.
In conclusion, Skype is a pleasure to use, and "just works" in most environments, regardless of firewalls or NAT; moreover interoperability between clients for different platforms seems perfect. What other internet telephony system can boast the same?
Sure, the feature list is not vast like other older and better-known applications, however this is a small price to pay for a system that works so well.
Transmitting voice needs bandwidth, there’s not much to be done about it: unfortunately, dialup users will hardly enjoy Internet Telephony in its full splendour. But if you have a good connection, you really have to give Skype a try; and should you miss a microphone, just plug a couple of ordinary earbuds to speak into instead: they'll decorously do the job!
About the author:
Alessandro Giusti is a 22 year old graduate student of Computer Engineering at Politecnico di Milano, Italy. His main interests are free software and everything about linux on the desktop.
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