As part of the merger, Skype's instant messaging functionality is now running on the backbone of the former Messenger service.
[1] Despite multiple name changes to the service and its client software over the years, the Messenger service is often referred to colloquially as "MSN", due to the history of MSN Messenger.
Organizations can also integrate their Microsoft Office Communications Server and Active Directory with the service.
In December 2011, Microsoft released an XMPP interface to the Messenger service.
[5] Microsoft offered the following instant messaging clients that connected to the Messenger service: A 2007 analysis of Messenger's Microsoft Notification Protocol, which is unencrypted, concluded that its design "did not follow several principles of designing secure systems", resulting in a "plethora of security vulnerabilities"; these vulnerabilities were demonstrated by successfully spoofing a user's identity.