T-Mobile on Tuesday announced the upcoming availability of the budget-friendly Nokia (NOK) Lumia 521 smartphone. The low-end device is equipped with a 4-inch 800 x 480-pixel display, a dual-core 1GHz processor and a 5-megapixel rear camera. The handset also includes 512MB of RAM, 8GB of internal storage, a microSD slot, HSPA+ 21Mbps connectivity and the Windows Phone 8 operating system. The Lumia 521 is scheduled to be released in May and will be available in Walmart (WMT), T-Mobile and Microsoft (MSFT) retail stores. Pricing information was not announced, although Nokia previously said that the device will cost around $180 without carrier subsidies.