T-Mobile is announcing that its wireless network is now HD voice-compatible nationwide, making it the second major carrier to offer this service. For users with compatible phones (which include the Samsung Galaxy S III and HTC One S), the service will offer a higher-quality voice service with reduced background ambient noise. That's not the only network-related news that T-Mobile is announcing — it also says its accelerating its rollout of its LTE network during the first half of the year. By mid-year, the carrier plans to cover 100 million people. We also confirmed with T-Mobile CTO Neville Ray that Las Vegas will be the first city with LTE coverage sometime in the next few weeks. The company was hoping to have it rolled out by CES but wasn't able to make that deadline. Between these announcements and T-Mobile's plan to offer unlimited 4G data without a contract, the carrier is making a major play to differentiate itself from its massive competitors.