when he first saw implementations of instant messaging, dorsey wondered whether the software's user status output could be shared easily among friends. he approached odeo, which at the time happened to be interested in text messaging. dorsey and biz stone decided that sms text suited the status-message idea, and built a prototype of twitter in about two weeks. the idea attracted many users at odeo and investment from evan williams, a co-founder of that firm in 2005 who had left google after selling pyra labs and blogger.