MSN Protocol Version 9
MSNP9 was introduced with MSN Messenger 6.0. Most of the changes in MSNP9 exist solely to support MSNC1 (also known as P2P transfers). Connecting with the Messenger Service using MSNP9 is not much different from MSNP8
MSNP9 is no longer supported by the notification server (noted as of 2010), although MSNP8 is still supported.