Windows Messenger lets you see when your friends, family and colleagues are online, send an instant message, send a file, have a voice chat or a video conversation, and engage in other collaborative efforts. Windows Messenger is easy to use, delivers great voice and video quality, and enables cool, new innovation with lots of other products and services you use every day. Windows Messenger version 4.5 added the ability for you to make phone calls from your computer to a phone almost everywhere in the world for a very low rate using the service provider you choose.

The Windows XP operating system comes with Windows Messenger 4.0 already installed. If you have Windows XP, you can now get the latest update—Windows Messenger 4.6.

Enterprise customers who have Microsoft Exchange 2000 Server get improved support with a special version of Windows Messenger 4.5. The special version makes deploying and using Windows Messenger within these environments faster and easier. Go to the Microsoft Exchange Server Web site to get more information about this special version of Windows Messenger 4.5 for Exchange 2000 Server Instant Messaging Service.

• Add-ins for Windows Messenger
  This new architecture allows a variety of third party developers to extend Windows Messenger 4.6 with exciting features, such as e-mail integration, chat, mobile text messaging, and more. These add-ins make Windows Messenger even more useful and fun for you, while the add-in architecture provides new opportunity for others in the industry to create new, innovative offerings.
  
  See a list of available add-ins for Windows Messenger.
  
  Third party developers interested in offering add-ins for Windows Messenger, click here to learn more.
  
• Additional computer-to-phone service options
  Enterprise organizations can customize the phone-dialer window in Windows Messenger to route computer-to-phone calls through the service provider your enterprise IT department selects. This can reduce the cost of long distance voice calls for your organization and enable new services that integrate with Windows Messenger. -And you benefit from the convenience of calling right from your computer.
  
• Other improvements
  This update also provides some enhancements to Help, clarifications within error messages, more flexibility in re-sizing the Conversation Window, and other minor performance improvements.

Note Calls placed using MSN Messenger Service 3.x, MSN Messenger, or Windows Messenger are free when made from a computer to a computer. Computer-to-computer calls can be made if both parties are using MSN Messenger or Windows Messenger. Note: If you are still using MSN Messenger Service version 3.x, you will be able to call only those computers that also have MSN Messenger Service version 3.x. To place calls from a computer to a telephone or mobile device, you must have MSN Messenger 4.5 or higher or Windows Messenger 4.5 or higher and a prepaid account with a voice service provider. All fees for such calls will be deducted from this account. However, please note that any standard phone charges and connect-time charges you normally pay for your Internet service provider (ISP), telephone, cell phone or mobile device service will still apply when you place calls using MSN Messenger. Certain country restrictions may also apply; void where prohibited by law. Internet calls are regulated and blocked by law in certain countries. Computer-to-phone calls require a Microsoft Passport, an MSN Hotmail® account, or an MSN Internet access account; multimedia computer; 33.6 Kbps modem; sound card; speakers; microphone; and Internet access. The listed voice service providers make voice transmission services available to users of MSN Messenger 4.5 and higher. Subject to change without notice.

Note: Actual requirements will vary based on your system configuration and the applications and features you choose to install. Additional available hard disk space may be required if you are installing over a network.

1. Double-click the icon on the taskbar to use Windows Messenger. (Windows Messenger starts automatically every time you open Windows.)
2. If you don't see the icon in the taskbar, click Start, point to Programs, and then click Windows Messenger.