Iphone App - voice messages

i want to build an iphone app to send short voice messages to a contact. Usage: i have a buddy list, clicking on a buddy i can record a small voice message, and the buddy will receive it (if connected with an alert, or if not connected with a push) it must work like a simple IM Function: - push notifications - text / photo messages - groups (send a message to a group) - scan my iphone contact list to find if someone uses this app - ads Server Side: users must subscribe, they get a password etcetera... - php / mysql system to manage all the functionalities The software must be complete, (simple graphic, icons, server side) let's say that it's considered finished when it's ready to be sent to the app store. tell also if you can do it in future for win, android, blackbarry and symbian. thanks