Android & iOS based Mobile Softphone App

Need developers for Android and iOS to build a mobile softphone app that is highly secure, standards-based mobile VoIP softphone that works over both 3G and Wi-Fi networks. App should be able to use the device’s existing contact list, facilitate easy and effective communication management with an intuitive interface. Have the ability to swap between two calls, merge calls and perform attended and unattended transfers. Incase the project is succesful the developers will be given a full-time job oppurunity with excellent remuneration.