There is only one file type that uses the .ULW extension:
u-Law Audio File
Uncompressed audio file format used in US telephony applications; contains raw CCITT G.711 u-law (pronounced "myoo-law") audio data that has not been encoded or compressed.
No standard file extension is defined for u-law files, but .ULAW may also be used.
Updated: June 20, 2009