The 35 Carbon, 50 Platinum and 53 Platinum all cater to the budget, carrier-independent crowd with common foundations of unlocked 7.2Mbps HSPA 3G, dual SIM slots (only one being 3G) and stock Android.
The goal was to establish and encourage the adoption of a common set of standards that would bring a 3G-like end-user experience to Wi-Fi by facilitating an automatic network discovery, selection and authentication of carrier-operated Wi-Fi networks.