Build a Website chat/picture messenger

HI I need a simple website built. The website will be back of my normal website I will dedicate a folder/sub domain for this. Its purpose is : 1. I want a application where people can text and send pictures via my server to peoples mobile phones. 2. people should be able to register with their numbers and the script should be able to retrieve everyone's mobile numbers of family and friends and send them a message they are using my services. I will at a later stage convert it into an app for the android market.