T-Mobile hopes to have its network ready for iPhone users by the fourth quarter of this year. AllThingsD reports that T-Mobile CTO Neville Ray, speaking at a dinner event in New Orleans on Monday, said that the effort to move much of its HSPA+ network over to the iPhone-friendly 1900 MHz spectrum should reach a critical mass in the fourth quarter of 2012. Ray declined to comment on whether the company would target iPhone users in a marketing push,…