When is 'Friends' character Phoebe Bouffay's birthday?

Phoebe's birthday is somewhat of a mystery because throughout the entire series, she has celebrations at different times of the year. The concensus is that it is sometime between September and January, but in one episode she tells her brother (played by Giavani Ribisi) that it is in mid February. Here is the actual listing from Wikipedia...

There is some confusion as to the date of Phoebe's birthday, as several dates are mentioned throughout the show. First, in Season 1's The One Where Nana Dies Twice, which aired in November, Rachel mentions going to Phoebe's birthday party, though she had only known her since September. Then, in January of Season 1, Phoebe had another birthday party. In season 3, she told her brother that her birthday was in mid-Febrary, and by season 9's The One With Phoebe's Birthday Dinner, her birthday was taking place close to Halloween. Many believe that because Phoebe grew up on the street, she really has no idea when her birthday is; however a point was made in the series of the fact that Phoebe's twin sister Ursula celebrated her birthday on the same day as Phoebe in the aforementioned January Season 1 episode.