Nowadays, it seems like everyone has a plan to help you part ways with a smartphone in return for some sort of store credit or, in a few cases, cash. Apple's doing it.GameStop's doing it. Amazon's doing it. You get the point. Starting on September 21st in the US, we'll be adding giant retailer Walmart to the list of companies currently offering a way to trade-in smartphones. The newfound program, powered by CExchange, is slated to be open in over 3,600 stores across the country (including Sam's Club locations); Walmart says its program will offer customers instant credit which can then be applied towards a shiny new handset. Obviously, the value will depend on the device's overall condition, so don't expect to get too much for thatshattered iPhone you've been rocking the past few months.