chat Software creation! prefer already made sotwares,

Hello, We are looking for a developer who can provide us with a software similar to Skype/paltalk. it doesn't have to be the exact match but some features such as invite/add people, camera/webcam/audio/video chat functions, being able to make calls to phones, purchase credits etc etc are necessary. We prefer already developed applications but if you can provide us with the program within a very short time then you re welcome to bid. Past related works must be shown as it is a must. VERY IMPORTANT: ********This must be a desktop application similar to skype which the users will download and install on their computers********. The budget is $700. Good luck and happy bidding.