[5][6] In June 2009, Microsoft reported the service attracted over 330 million active users each month, placing it among the most widely used instant-messaging clients in the world.

Teams inherited the Microsoft accounts architecture, allowing users to invite contacts from the discontinued services, MSN Messenger and Skype.

America Online continually tried to block Microsoft from having access to their service until eventually the feature was removed, and it has not re-surfaced in any later versions of the software.

[10] AOL did this by exploiting a buffer overflow bug in AIM, which causes it to execute a bit of machine code sent by the server.

It included file transfers and PC-to-PC and PC-to-phone audio capabilities with Net2Phone and Callserve,[13] two of the larger VoIP providers.

It included major changes to the user interface, the ability to group contacts, and support for voice conversations.

MSN Messenger 6.0 was a major overhaul of the whole platform, upgrading its simple text-based interface to include customizable elements such as emoticons, personalized avatars, and backgrounds.

Additionally, a new Voice Clips feature allowed users to hold down F2 and record a message for a maximum of 15 seconds and send it to the recipient.

Major changes and additions included the introduction of Windows Live Contacts, the reintroduction of single file transfer, improvements to the "Add a Contact" dialog box, improved color themes, minor changes in the conversation window, and revert of the "Busy" status icon back to the normal dash icon and a redesign of the log in page.

The main authentication system, Microsoft Passport Network, was replaced with Windows Live ID at the same time.

These include the addition of the roaming identity feature (so that the same user's display name and picture would appear on any computer), a new contact card appearance, a "recently used" list for the emoticon, wink, display picture and background menus, an SMS phone book in the main menu allowing the association and editing of a phone number to the contact and allowing text messaging to a contact, a "sign out" button, a "report abuse" option in the help menu, interoperability with Yahoo!

Messenger, and improvements to user status on Windows Vista[24] A minor update, the Windows Live Messenger 8.1 Beta 1 Refresh, was released on December 13, 2006,[6] and fixed bugs that were causing some people to be unable to sign in and others unable to see their contact list.

[27] On September 12, 2007, the Windows Live Messenger blog posted a fix that resolved a security problem.

[citation needed] In a presentation to the Georgia Institute of Technology's IEEE Student Branch, Microsoft employee Andrew Jenks reported that the Messenger team had been working on multi-person audio/video chat, and they are also attempting to create interoperability with AIM/XMPP/ICQ.

[citation needed] News web site LiveSide published an article on September 4, 2008, with screenshots of M2 of the newly minted "Windows Live Messenger 2009", which had become version 14.0 instead of 9.0 as previously expected.

LiveSide summarized its new features, including protection against messaging spam, the ability to stay signed into the application from several computers (referred to as "Multiple Points of Presence Support"), animated GIF files in the photo area, per-contact customized sounds for various user actions, and clickable URLs in the status area.

The ability to submit feedback, however, was restricted to select participants of the Microsoft Connect closed beta program.

However, as the software was designed for private beta testing, non-beta testers cannot sign into this leaked build.

[59] On February 15, 2013, ZDNet wrote the discontinuation email was only sent to one percent of Messenger users, a test group.

Users can also post status updates and photos directly to the connected services within Windows Live Messenger.

Additionally, a user can start conversations even when their status is set to Appear Offline in Windows Live Messenger 2009 or before.

The lack of proper encryption also makes wiretapping friend lists and personal conversations a trivial task, especially in unencrypted public Wi-Fi networks.

For example, the user can not send the links to The Pirate Bay's pages neither from the Windows Live Messenger, nor through other clients supporting the protocol.

[70] The i'm initiative was a program Microsoft launched in March 2007, that connects the user with ten organizations dedicated to social causes through Windows Live Messenger, only for conversations sent or received in the USA.

Every time someone had a conversation using i'm, Microsoft Corp. shared a portion of the program's advertising revenue with the organization of the user's choice.

[citation needed] Windows Live Messenger support was included in the Xbox 360 spring 2007 dashboard update released on May 9, 2007.

[83] Starting in the summer of 2000, the Microsoft-owned web access product MSN TV (then known as WebTV) introduced a software upgrade for users of its internet terminals that added a basic messaging client among other features.

[84] The client for the original WebTV/MSN TV internet terminals supported basic presence, plain text messages (no graphical emoticons), and buddy lists, with the overall WebTV/MSN TV service hosting services for users to add, remove, or block Messenger contacts and manage their Messenger settings.

[85] A client for Windows Live Messenger was developed by Microsoft for the Symbian S60 Platform commonly used on mobile phones such as Nokia smartphones and released on August 23, 2007, to selected markets.

[87] As of February 2009, Microsoft stopped charging for Windows Live Mobile and the service is now offered for free.