RadioShack, or The Shack as it now likes to be called, keeps turning in impressive financial results, mainly due to its mobile-phone selling success. Net income in its Q1 hit $50.1 million, up from $43.1 million in the same year-ago period, and same-store sales rose 4.7%Sales got a boost by the addition of T-Mobile to its wireless service providers, adding it to Sprint Nextel and AT&T. It also started selling iPhones last year.But the company faces possible major competition from Best Buy, which could add 1,000 mobile phone stores to its arsenal. However, the retailer is fighting back with kiosks in stores like Target and Sam's Club.Also rumors of Best Buy or a private equity firm acquiring RadioShack seem less unlikely. Best Buy can probably get good real estate for cheap in this environment without needing to purchase a huge portfolio of stores, and RadioShack's stock is reportedly valued too high for another potential takeover.Can RadioShack sustain these strong results, or will other competitors in the wireless arena, like Best Buy and Walmart, overtake the retailer?ALSO: A Website to Sell Surplus Real Estate Won't Revive Sears