What is the name of Phoebe's birth mother?

In Friends, Phoebe Buffay's birth mother is named Phoebe Abbott. This is revealed in later seasons when Phoebe discovers that the woman she knew as her mother (Lilly) was actually her surrogate/foster mother, and her biological mother is also named Phoebe. This is why Phoebe's middle name is also somewhat unusual in the family context. Lily was the woman who raised her, Nora is not her mother's name in the show.