Cross platform Bluetooth number exchange

I need to have an application developed that can exchange a 20 digit to 28 digit number between two systems. I need the application to work with Ipad, Iphone, Android and WebOS. The devices should recognize each other and then ask if they can transfer the numbers to each other. This is part of a larger scale project and all code must be provided to integrate into the larger project. The devices need to recognize that the application is nearby. The devices must ask if an exchange is to be made. When both devices accept the exchange, the numbers are then available for a database.