Hi,
Thank you for using libphonenumber!
Usually, when parsing, we remove a country's national or trunk prefix, so we can store a normalized form of the number.
In this case
+115005550009, '+1' is country code and the next '1' is the national prefix of the United States. After parsing we get the 10 digit number
5005550009.
NPA 500 is categorized as
'Personal Numbers' and the complete '500-555' range is valid since 09/21/2023 as per NANPA.
Therefore it is a valid and a possible number and the same is supported by our library.