Probably, Nokia would launch the Asha 501 which has been in the news off late. According to rumors, Nokia Asha 501 is to come with design like the Nokia Lumia phones. Further the Asha 501 is said to come with a 5 megapixel camera with LED flash, and a slightly larger display than Asha 311 which has a 3 inch touchscreen. Most likely this handset will have at least a 1 GHz processor.
The wording of the invite makes us believe that it is going to be the biggest Asha series launch and Asha 501 is the biggest in Asha series that we know of.
Nokia is reemphasizing on its Asha series of phones to strengthen its market hold. Recently Stephen Elop, Nokia's chief executive officer, had also emphasized that saying, "We have to make sure the product portfolio is as competitive as possible. We are due for a significant refresh."