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On a related note, Google talk uses the same GIPS VoiceEngine.

Also this is a good way to compete with Yahoo! Messenger, which was recently upgraded to use the same voice codec as skype.

Furthermore, Skype uses technology from the Global IP Sound, which announced availability of their VoiceEngine Mobile platform for the Symbian.

So it should be here Soon(TM)

"Global IP Sound provides voice processing software to Skype's peer-to-peer voice-communications software."

Oh, and, "Global IP Sound (GIPS), a leading provider of embedded voice-processing solutions for the Voice over IP (VoIP) market, today announced an OEM license agreement with Google for voice processing solutions."

"Global IP Sound provides voice processing software to Skype's peer-to-peer voice-communications software."

Oh, and, "Global IP Sound (GIPS), a leading provider of embedded voice-processing solutions for the Voice over IP (VoIP) market, today announced an OEM license agreement with Google for voice processing solutions."

Skype supports multiple platforms (Windows, Linux, MacOS X, PocketPC w/ WiFi). I use it under Linux (using the version one step back from the latest, since the latest has bugs) and it works beautifully. Plus it uses some form of technique (a P2P network) to get around firewall limitations as much as possible. As I understand it, the CODECs it uses (probably along with the network stack) are provided by http://www.globalipsound.com/ (in a PC-to-PC skype call it says the "ISAC" codec is being used-- http://www.globalipsound.com/datasheets/iSAC.pdf)

They have the SkypeOut/SkypeIn service which allows you to make outgoing calls, and SkypeIn allows you to own a telephone number in a number of different countries (USA, UK, France, Hong Kong, Denmark, Finland, Sweden, Poland currently) which link to your account. When you're using these I don't think Skype uses the ISAC codec, it uses something with crappier quality.

(note: I don't work for them, I've just been a happy customer for the past few months, especially with the Linux support.)

Skype supports multiple platforms (Windows, Linux, MacOS X, PocketPC w/ WiFi). I use it under Linux (using the version one step back from the latest, since the latest has bugs) and it works beautifully. Plus it uses some form of technique (a P2P network) to get around firewall limitations as much as possible. As I understand it, the CODECs it uses (probably along with the network stack) are provided by http://www.globalipsound.com/ (in a PC-to-PC skype call it says the "ISAC" codec is being used-- http://www.globalipsound.com/datasheets/iSAC.pdf)

They have the SkypeOut/SkypeIn service which allows you to make outgoing calls, and SkypeIn allows you to own a telephone number in a number of different countries (USA, UK, France, Hong Kong, Denmark, Finland, Sweden, Poland currently) which link to your account. When you're using these I don't think Skype uses the ISAC codec, it uses something with crappier quality.

(note: I don't work for them, I've just been a happy customer for the past few months, especially with the Linux support.)

The about box in the windows client says that it includes audio components from Global IP Sound. I don't know anything about the Jabber protocol's capabilities but maybe the whole voice chat thing is the selling point?

If only that worked for your fps.

Skype is very open: you can just send it text based commands. They even have a developer zone, so it looks like the parent was just trolling.

The voice protocol is provided by GIPS, they are quite open too about how their codec works with dynamic buffering.

According to this article, Skype licensed a proprietary codec from Global IP Sound.

As for spyware, a little research into the history of the Kazaa client would reveal that the people who introduced the spyware did so after they bought the technology from the developers. The Skype people are the original developers and had nothing to do with the spyware included in the install. Remember for a time you could download the Morpheus client and participate on the same P2P network as Kazaa without spyware. It wasn't until Morpheus and Kazaa had a falling out and Morpheus no longer worked on the Kazaa network that you saw the spyware free KazaaLite clients coming out.

• They're using audio codecs from Global Ip Sound, who make codecs that are more tolerant of high packet loss than most of the low-bit-rate public-standard codecs, and also better-than-telco-quality higher-bandwidth codecs. It looks like Global IP is working on getting some of their codecs into the standards track.
• They view NAT traversal as a critical design element, because NAT's become extremely widespread (in spite of being evil breakage of the end-to-end paradigm), so they've done more than the SIP standards do to simplify that. (SIP came from Internet people, so it was far, far better than the H.323 stuff that came from the ISDN crowd, and it's easy to set up firewalls for SIP transparency, but NAT traversal takes extra work.)
• They view security as a critical requirement, so they've got modern crypto algorithms like AES in there, and from a performance standpoint it's a really big win to encrypt the data packets rather than using IPSEC tunnels, because VOIP data is inherently small compared to the headers. Unfortunately, because of their attitudes about proprietariness and no public documentation, it's not possible for the crypto community to examine their protocols or code, and most crypto mistakes these days are made in protocol implementations, not in the fundamental algorithms, so even though they use AES and Diffie-Hellmann and long enough keys, that doesn't mean they're not totally hosed.
• P2P is fun, and can scale well by taking load off the central server, and the Skype folks don't want to run a huge central server. This has some conveniences for their design (supernodes for NAT traversal assistance, etc.), and creates some interesting security tradeoffs (no central point of attack, but widely distributed local attack points) which are unfortunately covered up by the lack of protocol documentation.

• They're using audio codecs from Global Ip Sound, who make codecs that are more tolerant of high packet loss than most of the low-bit-rate public-standard codecs, and also better-than-telco-quality higher-bandwidth codecs. It looks like Global IP is working on getting some of their codecs into the standards track.
• They view NAT traversal as a critical design element, because NAT's become extremely widespread (in spite of being evil breakage of the end-to-end paradigm), so they've done more than the SIP standards do to simplify that. (SIP came from Internet people, so it was far, far better than the H.323 stuff that came from the ISDN crowd, and it's easy to set up firewalls for SIP transparency, but NAT traversal takes extra work.)
• They view security as a critical requirement, so they've got modern crypto algorithms like AES in there, and from a performance standpoint it's a really big win to encrypt the data packets rather than using IPSEC tunnels, because VOIP data is inherently small compared to the headers. Unfortunately, because of their attitudes about proprietariness and no public documentation, it's not possible for the crypto community to examine their protocols or code, and most crypto mistakes these days are made in protocol implementations, not in the fundamental algorithms, so even though they use AES and Diffie-Hellmann and long enough keys, that doesn't mean they're not totally hosed.
• P2P is fun, and can scale well by taking load off the central server, and the Skype folks don't want to run a huge central server. This has some conveniences for their design (supernodes for NAT traversal assistance, etc.), and creates some interesting security tradeoffs (no central point of attack, but widely distributed local attack points) which are unfortunately covered up by the lack of protocol documentation.

Go to Help -> About... there you can see the
licenses and also what codecs Skype is using.
Such as Global IP Sound and
Joltid