How does skype supports all the mobile platforms?

Question

I am developing an application which is kind of similar to Skype with some more features. I am amused and surprised by Skype's response to various mobile platforms i.e. iPhone, Android, BlackBerry, Symbian, Bada OS etc. I want to know how Skype is able to so rapidly release versions for iPhone, Android and Blackberry? Do they write code targeting every platform separately or do they write code once and then use some utility to make it available across all platforms? As a developer I am kind of curious to know the real technique which can be the reason of behind the scene magic. Any clues? Answers with valid sources and references are more appreciated. JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

They are an $800 million/year revenue company, its probably not a huge deal to support many platforms. From Quora : http://www.quora.com/Skype/What-programming-language-was-Skype-originally-written-in The original internal alpha version of UI was built in QT and we hoped to do few platforms at same take. However the result looked like crap, our progress seemed slow and we ditched the QT about 2 months before public beta release. Delphi was chosen because our first senior UI developer was very skilled at Delphi (besides dozen other languages-environments) and we saw D as most productive, fastest, efficient way to build our app given our team/lead developer skills and also getting very good UX on MSWin platform. For linux the QT remained and on OSX it has been Cocoa from the start. The functional core components which did the heavy lifting under the UI have always been the same C/C++ as Ahti pointed out.