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Comment by kogus | Hacker News Reader

Anybody know what technologies / languages they've used to build Skype?

C++ as far as I know. Skype has its roots in Kazaa's file sharing technology, they use a proprietary P2P network to get around routers and firewalls - something that VOIP services lack. It also does direct high quality connections where available.

what do you mean exactly by getting around routers and firewall? I've been working with freeswitch and NAT is really a no brainer if you have a UPnP router. Firewalls? Does skype get around firewalls that are explicitly configured to block it? As far as 'direct high quality connections' are concerned, even freeswitch does that, it only does the SIP signalling and lets the media stream exchange directly between the endpoints, given that both can see each other directlly (no NAT in between).

NAT is really a no brainer if you have a UPnP router

Skype does much better than that. AFAIK they can traverse NATs and firewalls that don't support UPnP; they can fall back to TCP if UDP doesn't work; if all else fails they have a network of supernodes to relay traffic.

I just mentioned a UPnP router because I think most home routers I see here given buy ISPs support it. There are other ways as well, and yes that includes falling back to TCP if UDP doesn't work.

I'm just saying that everything skype does can be done with OSS using open standards. That skype is in any way technologically superior is mostly result of excessive FUD campaigns IMHO. :)

Skype has a big 'it just works' factor. With most sip and other products you had to deal with arcane stun server setup, and other configuration that would confuse most people. And on top of that the quality was significantly better than other options at the time such as msn and others. The combination of higher voip quality, ease of use, and no tech wizardry required (and a lot of marketing after they got rid of the tech hindrances) it went off.

Indeed. Whenever I looked in magazines targeted at casual internet users over the past decade, Skype was always the service recommended as "VOIP". It works through practically any network problem, which makes it ideal for hotels and from use inside corporate networks.

The quality is high, it's highly accessible and it doesn't have an equal competitor. Even the instant messaging services that do voice and video are poor alternatives. It has also been used for several years by feature phones and smart phones - some as their main selling point.

Essentially, its a pseudo standard used by most people.

Yes, i totally agree with all of that. They had a huge 'first mover' advantage. Just that there's no tech-wizardry involved in there closed protocol.

I was curious; looks like they've used a few different things to put it together; everything from Delphi to Objective C.

Source: http://en.wikipedia.org/wiki/Skype

To be more specific, looks like it goes:

Windows: Delphi Linux: C++ OS X: Objective-C

http://www.answerbag.com/q_view/2124396

They use postgresql i believe.

obfuscation

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