The Single Sign-on (SSO) service has now been connected to the eduGAIN service. This allows you to sign-on with an account from any of the ID providers within the eduGAIN federation. Over 43 national federations are member of eduGAIN with a combined total of over 4000 educational institutes as member.

For an overview of eduGAIN see

http://www.edugain.org/technical/

https://en.wikipedia.org/wiki/EduGAIN