T-Mobile is preparing to unveil its nation-wide 3G network on October 1st, according to a poster that reveals a selection of major US cities to first receive the service. While members of the community previously tossed around the date, the poster confirms that users in Los Angeles, as Vegas, Dallas, New Jersey, Washington, and 21 other cities will be able to use 3G-capable T-Mobile devices with the network’s faster transfer rates and superior call quality.