You can invite users to provide permission to display their online presence. There are two ways to do this:

• Delegated Authentication— Add a link to the consent page. When a user clicks the link, the user is taken to a Windows Live Messenger consent page for Delegated Authentication. This is the preferred method of obtaining consent for the Presence API.
  After the user has provided consent, the user is directed back to the URL that you specified in the consent-request URL. A consent token is posted back to the return URL. You can then use the user’s delegation token (a component of the consent token) to query for the user’s online presence.
  For specific information about using this method, see Consent Request URL for the IM Control.
  
• Windows Live Messenger Web Settings—To enable this functionality, add a link to the signup page. When a user clicks the signup link, the user is taken to a Windows Live Messenger settings page. After signup is complete, the user is directed back to the URL that you specified in the signup link. You can then use the user's ID to query for the user’s online presence.
  For specific information about using this method, see IM Control Signup URL.