Microsoft has added support for single sign-on and mobile devices to its Windows Live ID authentication service.

Executives posted the updates to Windows Live on separate blog entries. Windows Live ID is the gateway to other Windows Live services, such as email, instant messaging, blogging and security.

Users with multiple sign-ons for various Windows Live services can now unify them through one ID and password, according to a blog entry from Jeff Steinbok, a member of Microsoft's Live Spaces development team. To set this up, users can go to the Windows Live account site and look for the section called Linked Windows Live IDs. A user can add IDs to a single "linked" ID and password so they only need to sign in once to use various Windows Live services.

Microsoft also is giving users the ability to sign up for a Windows Live ID from mobile devices, according to a blog post by Phil Holden, director of online services. Microsoft designed it to work with built-in mobile phone browsers and users only need a data plan from a mobile carrier to get started.

To sign up for a Windows Live ID from a mobile phone, users have two options they can use directly from their mobile browser, according to Holden. They can go directly to the Windows Live account-creation site or go to http://mobile.live.com and find a Windows Live service, such as Hotmail, and select "Get a Windows Live ID."

Microsoft is trying to make its Windows Live services more appealing and widely accessible to users as it competes with Google and Yahoo for advertising revenue from its business and consumer web-based services.