Google has released an experimental mobile phone to employees, with access to the public expected to be offered in January. Asking employees to test products has become an established tactic for the search engine giant. A phone from Google has been rumoured for a while, and could revolutionise mobile phone use, with people using social messaging services to communicate rather than making calls, which will weaken the position of the mobile phone networks. The phone is expected to be called Nexus One. It will run the Android operating system for mobiles.